Wala shell

Advanced PHP File Manager

Server IP: 127.0.0.1 | PHP Version: 8.3.30 | Domains Hosted: 54

Name	Size	Last Modified	Actions
📁 ..	-	2026-03-09 14:41
📄 sqlite3.h /* 2001 September 15 The author disclaims copyright to this source code. In place of a legal notice, here is a blessing: May you do good and not evil. May you find forgiveness for yourself and forgive others. May you share freely, never taking more than you give. ********************************************************************* This header file defines the interface that the SQLite library presents to client programs. If a C-function, structure, datatype, or constant definition does not appear in this file, then it is not a published API of SQLite, is subject to change without notice, and should not be referenced by programs that use SQLite. Some of the definitions that are in this file are marked as "experimental". Experimental interfaces are normally new features recently added to SQLite. We do not anticipate changes to experimental interfaces but reserve the right to make minor changes if experience from use "in the wild" suggest such changes are prudent. The official C-language API documentation for SQLite is derived from comments in this file. This file is the authoritative source on how SQLite interfaces are suppose to operate. The name of this file under configuration management is "sqlite.h.in". The makefile makes some minor changes to this file (such as inserting the version number) and changes its name to "sqlite3.h" as ** part of the build process. / #ifndef _SQLITE3_H_ #define _SQLITE3_H_ #include <stdarg.h> / Needed for the definition of va_list / / ** Make sure we can call this stuff from C++. / #ifdef __cplusplus extern "C" { #endif / ** Provide the ability to override linkage features of the interface. / #ifndef SQLITE_EXTERN # define SQLITE_EXTERN extern #endif #ifndef SQLITE_API # define SQLITE_API #endif #ifndef SQLITE_CDECL # define SQLITE_CDECL #endif #ifndef SQLITE_STDCALL # define SQLITE_STDCALL #endif / These no-op macros are used in front of interfaces to mark those interfaces as either deprecated or experimental. New applications should not use deprecated interfaces - they are supported for backwards compatibility only. Application writers should be aware that experimental interfaces are subject to change in point releases. These macros used to resolve to various kinds of compiler magic that would generate warning messages when they were used. But that compiler magic ended up generating such a flurry of bug reports that we have taken it all out and gone back to using simple ** noop macros. / #define SQLITE_DEPRECATED #define SQLITE_EXPERIMENTAL / ** Ensure these symbols were not defined by some previous header file. / #ifdef SQLITE_VERSION # undef SQLITE_VERSION #endif #ifdef SQLITE_VERSION_NUMBER # undef SQLITE_VERSION_NUMBER #endif / CAPI3REF: Compile-Time Library Version Numbers ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header evaluates to a string literal that is the SQLite version in the format "X.Y.Z" where X is the major version number (always 3 for SQLite3) and Y is the minor version number and Z is the release number.)^ ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer with the value (X1000000 + Y1000 + Z) where X, Y, and Z are the same numbers used in [SQLITE_VERSION].)^ The SQLITE_VERSION_NUMBER for any given release of SQLite will also be larger than the release from which it is derived. Either Y will be held constant and Z will be incremented or else Y will be incremented and Z will be reset to zero. Since version 3.6.18, SQLite source code has been stored in the <a href="http://www.fossil-scm.org/">Fossil configuration management system</a>. ^The SQLITE_SOURCE_ID macro evaluates to a string which identifies a particular check-in of SQLite within its configuration management system. ^The SQLITE_SOURCE_ID string contains the date and time of the check-in (UTC) and an SHA1 hash of the entire source tree. See also: [sqlite3_libversion()], [sqlite3_libversion_number()], [sqlite3_sourceid()], ** [sqlite_version()] and [sqlite_source_id()]. / #define SQLITE_VERSION "3.8.10.2" #define SQLITE_VERSION_NUMBER 3008010 #define SQLITE_SOURCE_ID "2015-05-20 18:17:19 2ef4f3a5b1d1d0c4338f8243d40a2452cc1f7fe4" / CAPI3REF: Run-Time Library Version Numbers KEYWORDS: sqlite3_version, sqlite3_sourceid These interfaces provide the same information as the [SQLITE_VERSION], [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros but are associated with the library instead of the header file. ^(Cautious programmers might include assert() statements in their application to verify that values returned by these interfaces match the macros in the header, and thus insure that the application is compiled with matching library and header files. <blockquote><pre> assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER ); assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 ); assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 ); </pre></blockquote>)^ ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION] macro. ^The sqlite3_libversion() function returns a pointer to the to the sqlite3_version[] string constant. The sqlite3_libversion() function is provided for use in DLLs since DLL users usually do not have direct access to string constants within the DLL. ^The sqlite3_libversion_number() function returns an integer equal to [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns a pointer to a string constant whose value is the same as the [SQLITE_SOURCE_ID] C preprocessor macro. See also: [sqlite_version()] and [sqlite_source_id()]. / SQLITE_API SQLITE_EXTERN const char sqlite3_version[]; SQLITE_API const char SQLITE_STDCALL sqlite3_libversion(void); SQLITE_API const char SQLITE_STDCALL sqlite3_sourceid(void); SQLITE_API int SQLITE_STDCALL sqlite3_libversion_number(void); / CAPI3REF: Run-Time Library Compilation Options Diagnostics ^The sqlite3_compileoption_used() function returns 0 or 1 indicating whether the specified option was defined at compile time. ^The SQLITE_ prefix may be omitted from the option name passed to sqlite3_compileoption_used(). ^The sqlite3_compileoption_get() function allows iterating over the list of options that were defined at compile time by returning the N-th compile time option string. ^If N is out of range, sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_ prefix is omitted from any strings returned by sqlite3_compileoption_get(). ^Support for the diagnostic functions sqlite3_compileoption_used() and sqlite3_compileoption_get() may be omitted by specifying the [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time. See also: SQL functions [sqlite_compileoption_used()] and [sqlite_compileoption_get()] and the [compile_options pragma]. / #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS SQLITE_API int SQLITE_STDCALL sqlite3_compileoption_used(const char zOptName); SQLITE_API const char SQLITE_STDCALL sqlite3_compileoption_get(int N); #endif / CAPI3REF: Test To See If The Library Is Threadsafe ^The sqlite3_threadsafe() function returns zero if and only if SQLite was compiled with mutexing code omitted due to the [SQLITE_THREADSAFE] compile-time option being set to 0. SQLite can be compiled with or without mutexes. When the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes are enabled and SQLite is threadsafe. When the [SQLITE_THREADSAFE] macro is 0, the mutexes are omitted. Without the mutexes, it is not safe to use SQLite concurrently from more than one thread. Enabling mutexes incurs a measurable performance penalty. So if speed is of utmost importance, it makes sense to disable the mutexes. But for maximum safety, mutexes should be enabled. ^The default behavior is for mutexes to be enabled. This interface can be used by an application to make sure that the version of SQLite that it is linking against was compiled with the desired setting of the [SQLITE_THREADSAFE] macro. This interface only reports on the compile-time mutex setting of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but can be fully or partially disabled using a call to [sqlite3_config()] with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD], or [SQLITE_CONFIG_SERIALIZED]. ^(The return value of the sqlite3_threadsafe() function shows only the compile-time setting of thread safety, not any run-time changes to that setting made by sqlite3_config(). In other words, the return value from sqlite3_threadsafe() is unchanged by calls to sqlite3_config().)^ See the [threading mode] documentation for additional information. / SQLITE_API int SQLITE_STDCALL sqlite3_threadsafe(void); / CAPI3REF: Database Connection Handle KEYWORDS: {database connection} {database connections} Each open SQLite database is represented by a pointer to an instance of the opaque structure named "sqlite3". It is useful to think of an sqlite3 pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()] and [sqlite3_close_v2()] are its destructors. There are many other interfaces (such as [sqlite3_prepare_v2()], [sqlite3_create_function()], and [sqlite3_busy_timeout()] to name but three) that are methods on an sqlite3 object. / typedef struct sqlite3 sqlite3; / CAPI3REF: 64-Bit Integer Types KEYWORDS: sqlite_int64 sqlite_uint64 Because there is no cross-platform way to specify 64-bit integer types SQLite includes typedefs for 64-bit signed and unsigned integers. The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions. The sqlite_int64 and sqlite_uint64 types are supported for backwards compatibility only. ^The sqlite3_int64 and sqlite_int64 types can store integer values between -9223372036854775808 and +9223372036854775807 inclusive. ^The sqlite3_uint64 and sqlite_uint64 types can store integer values between 0 and +18446744073709551615 inclusive. / #ifdef SQLITE_INT64_TYPE typedef SQLITE_INT64_TYPE sqlite_int64; typedef unsigned SQLITE_INT64_TYPE sqlite_uint64; #elif defined(_MSC_VER) \|\| defined(__BORLANDC__) typedef __int64 sqlite_int64; typedef unsigned __int64 sqlite_uint64; #else typedef long long int sqlite_int64; typedef unsigned long long int sqlite_uint64; #endif typedef sqlite_int64 sqlite3_int64; typedef sqlite_uint64 sqlite3_uint64; / If compiling for a processor that lacks floating point support, substitute integer for floating-point. / #ifdef SQLITE_OMIT_FLOATING_POINT # define double sqlite3_int64 #endif / CAPI3REF: Closing A Database Connection DESTRUCTOR: sqlite3 ^The sqlite3_close() and sqlite3_close_v2() routines are destructors for the [sqlite3] object. ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if the [sqlite3] object is successfully destroyed and all associated resources are deallocated. ^If the database connection is associated with unfinalized prepared statements or unfinished sqlite3_backup objects then sqlite3_close() will leave the database connection open and return [SQLITE_BUSY]. ^If sqlite3_close_v2() is called with unfinalized prepared statements and/or unfinished sqlite3_backups, then the database connection becomes an unusable "zombie" which will automatically be deallocated when the last prepared statement is finalized or the last sqlite3_backup is finished. The sqlite3_close_v2() interface is intended for use with host languages that are garbage collected, and where the order in which destructors are called is arbitrary. Applications should [sqlite3_finalize \| finalize] all [prepared statements], [sqlite3_blob_close \| close] all [BLOB handles], and [sqlite3_backup_finish \| finish] all [sqlite3_backup] objects associated with the [sqlite3] object prior to attempting to close the object. ^If sqlite3_close_v2() is called on a [database connection] that still has outstanding [prepared statements], [BLOB handles], and/or [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation of resources is deferred until all [prepared statements], [BLOB handles], and [sqlite3_backup] objects are also destroyed. ^If an [sqlite3] object is destroyed while a transaction is open, the transaction is automatically rolled back. The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)] must be either a NULL pointer or an [sqlite3] object pointer obtained from [sqlite3_open()], [sqlite3_open16()], or [sqlite3_open_v2()], and not previously closed. ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. / SQLITE_API int SQLITE_STDCALL sqlite3_close(sqlite3); SQLITE_API int SQLITE_STDCALL sqlite3_close_v2(sqlite3); / The type for a callback function. This is legacy and deprecated. It is included for historical ** compatibility and is not documented. / typedef int (sqlite3_callback)(void,int,char, char); / CAPI3REF: One-Step Query Execution Interface METHOD: sqlite3 The sqlite3_exec() interface is a convenience wrapper around [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()], that allows an application to run multiple statements of SQL without having to use a lot of C code. ^The sqlite3_exec() interface runs zero or more UTF-8 encoded, semicolon-separate SQL statements passed into its 2nd argument, in the context of the [database connection] passed in as its 1st argument. ^If the callback function of the 3rd argument to sqlite3_exec() is not NULL, then it is invoked for each result row coming out of the evaluated SQL statements. ^The 4th argument to sqlite3_exec() is relayed through to the 1st argument of each callback invocation. ^If the callback pointer to sqlite3_exec() is NULL, then no callback is ever invoked and result rows are ignored. ^If an error occurs while evaluating the SQL statements passed into sqlite3_exec(), then execution of the current statement stops and subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec() is not NULL then any error message is written into memory obtained from [sqlite3_malloc()] and passed back through the 5th parameter. To avoid memory leaks, the application should invoke [sqlite3_free()] on error message strings returned through the 5th parameter of of sqlite3_exec() after the error message string is no longer needed. ^If the 5th parameter to sqlite3_exec() is not NULL and no errors occur, then sqlite3_exec() sets the pointer in its 5th parameter to NULL before returning. ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec() routine returns SQLITE_ABORT without invoking the callback again and without running any subsequent SQL statements. ^The 2nd argument to the sqlite3_exec() callback function is the number of columns in the result. ^The 3rd argument to the sqlite3_exec() callback is an array of pointers to strings obtained as if from [sqlite3_column_text()], one for each column. ^If an element of a result row is NULL then the corresponding string pointer for the sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the sqlite3_exec() callback is an array of pointers to strings where each entry represents the name of corresponding result column as obtained from [sqlite3_column_name()]. ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer to an empty string, or a pointer that contains only whitespace and/or SQL comments, then no SQL statements are evaluated and the database is not changed. Restrictions: <ul> <li> The application must insure that the 1st parameter to sqlite3_exec() is a valid and open [database connection]. <li> The application must not close the [database connection] specified by the 1st parameter to sqlite3_exec() while sqlite3_exec() is running. <li> The application must not modify the SQL statement text passed into the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running. </ul> / SQLITE_API int SQLITE_STDCALL sqlite3_exec( sqlite3, /* An open database / const char sql, /* SQL to be evaluated / int (callback)(void,int,char,char), / Callback function / void , /* 1st argument to callback / char errmsg / Error msg written here / ); / CAPI3REF: Result Codes KEYWORDS: {result code definitions} Many SQLite functions return an integer result code from the set shown here in order to indicate success or failure. New error codes may be added in future versions of SQLite. ** See also: [extended result code definitions] / #define SQLITE_OK 0 / Successful result / / beginning-of-error-codes / #define SQLITE_ERROR 1 / SQL error or missing database / #define SQLITE_INTERNAL 2 / Internal logic error in SQLite / #define SQLITE_PERM 3 / Access permission denied / #define SQLITE_ABORT 4 / Callback routine requested an abort / #define SQLITE_BUSY 5 / The database file is locked / #define SQLITE_LOCKED 6 / A table in the database is locked / #define SQLITE_NOMEM 7 / A malloc() failed / #define SQLITE_READONLY 8 / Attempt to write a readonly database / #define SQLITE_INTERRUPT 9 / Operation terminated by sqlite3_interrupt()/ #define SQLITE_IOERR 10 / Some kind of disk I/O error occurred / #define SQLITE_CORRUPT 11 / The database disk image is malformed / #define SQLITE_NOTFOUND 12 / Unknown opcode in sqlite3_file_control() / #define SQLITE_FULL 13 / Insertion failed because database is full / #define SQLITE_CANTOPEN 14 / Unable to open the database file / #define SQLITE_PROTOCOL 15 / Database lock protocol error / #define SQLITE_EMPTY 16 / Database is empty / #define SQLITE_SCHEMA 17 / The database schema changed / #define SQLITE_TOOBIG 18 / String or BLOB exceeds size limit / #define SQLITE_CONSTRAINT 19 / Abort due to constraint violation / #define SQLITE_MISMATCH 20 / Data type mismatch / #define SQLITE_MISUSE 21 / Library used incorrectly / #define SQLITE_NOLFS 22 / Uses OS features not supported on host / #define SQLITE_AUTH 23 / Authorization denied / #define SQLITE_FORMAT 24 / Auxiliary database format error / #define SQLITE_RANGE 25 / 2nd parameter to sqlite3_bind out of range / #define SQLITE_NOTADB 26 / File opened that is not a database file / #define SQLITE_NOTICE 27 / Notifications from sqlite3_log() / #define SQLITE_WARNING 28 / Warnings from sqlite3_log() / #define SQLITE_ROW 100 / sqlite3_step() has another row ready / #define SQLITE_DONE 101 / sqlite3_step() has finished executing / / end-of-error-codes / / CAPI3REF: Extended Result Codes KEYWORDS: {extended result code definitions} In its default configuration, SQLite API routines return one of 30 integer [result codes]. However, experience has shown that many of these result codes are too coarse-grained. They do not provide as much information about problems as programmers might like. In an effort to address this, newer versions of SQLite (version 3.3.8 and later) include support for additional result codes that provide more detailed information about errors. These [extended result codes] are enabled or disabled on a per database connection basis using the [sqlite3_extended_result_codes()] API. Or, the extended code for the most recent error can be obtained using [sqlite3_extended_errcode()]. / #define SQLITE_IOERR_READ (SQLITE_IOERR \| (1<<8)) #define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR \| (2<<8)) #define SQLITE_IOERR_WRITE (SQLITE_IOERR \| (3<<8)) #define SQLITE_IOERR_FSYNC (SQLITE_IOERR \| (4<<8)) #define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR \| (5<<8)) #define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR \| (6<<8)) #define SQLITE_IOERR_FSTAT (SQLITE_IOERR \| (7<<8)) #define SQLITE_IOERR_UNLOCK (SQLITE_IOERR \| (8<<8)) #define SQLITE_IOERR_RDLOCK (SQLITE_IOERR \| (9<<8)) #define SQLITE_IOERR_DELETE (SQLITE_IOERR \| (10<<8)) #define SQLITE_IOERR_BLOCKED (SQLITE_IOERR \| (11<<8)) #define SQLITE_IOERR_NOMEM (SQLITE_IOERR \| (12<<8)) #define SQLITE_IOERR_ACCESS (SQLITE_IOERR \| (13<<8)) #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR \| (14<<8)) #define SQLITE_IOERR_LOCK (SQLITE_IOERR \| (15<<8)) #define SQLITE_IOERR_CLOSE (SQLITE_IOERR \| (16<<8)) #define SQLITE_IOERR_DIR_CLOSE (SQLITE_IOERR \| (17<<8)) #define SQLITE_IOERR_SHMOPEN (SQLITE_IOERR \| (18<<8)) #define SQLITE_IOERR_SHMSIZE (SQLITE_IOERR \| (19<<8)) #define SQLITE_IOERR_SHMLOCK (SQLITE_IOERR \| (20<<8)) #define SQLITE_IOERR_SHMMAP (SQLITE_IOERR \| (21<<8)) #define SQLITE_IOERR_SEEK (SQLITE_IOERR \| (22<<8)) #define SQLITE_IOERR_DELETE_NOENT (SQLITE_IOERR \| (23<<8)) #define SQLITE_IOERR_MMAP (SQLITE_IOERR \| (24<<8)) #define SQLITE_IOERR_GETTEMPPATH (SQLITE_IOERR \| (25<<8)) #define SQLITE_IOERR_CONVPATH (SQLITE_IOERR \| (26<<8)) #define SQLITE_LOCKED_SHAREDCACHE (SQLITE_LOCKED \| (1<<8)) #define SQLITE_BUSY_RECOVERY (SQLITE_BUSY \| (1<<8)) #define SQLITE_BUSY_SNAPSHOT (SQLITE_BUSY \| (2<<8)) #define SQLITE_CANTOPEN_NOTEMPDIR (SQLITE_CANTOPEN \| (1<<8)) #define SQLITE_CANTOPEN_ISDIR (SQLITE_CANTOPEN \| (2<<8)) #define SQLITE_CANTOPEN_FULLPATH (SQLITE_CANTOPEN \| (3<<8)) #define SQLITE_CANTOPEN_CONVPATH (SQLITE_CANTOPEN \| (4<<8)) #define SQLITE_CORRUPT_VTAB (SQLITE_CORRUPT \| (1<<8)) #define SQLITE_READONLY_RECOVERY (SQLITE_READONLY \| (1<<8)) #define SQLITE_READONLY_CANTLOCK (SQLITE_READONLY \| (2<<8)) #define SQLITE_READONLY_ROLLBACK (SQLITE_READONLY \| (3<<8)) #define SQLITE_READONLY_DBMOVED (SQLITE_READONLY \| (4<<8)) #define SQLITE_ABORT_ROLLBACK (SQLITE_ABORT \| (2<<8)) #define SQLITE_CONSTRAINT_CHECK (SQLITE_CONSTRAINT \| (1<<8)) #define SQLITE_CONSTRAINT_COMMITHOOK (SQLITE_CONSTRAINT \| (2<<8)) #define SQLITE_CONSTRAINT_FOREIGNKEY (SQLITE_CONSTRAINT \| (3<<8)) #define SQLITE_CONSTRAINT_FUNCTION (SQLITE_CONSTRAINT \| (4<<8)) #define SQLITE_CONSTRAINT_NOTNULL (SQLITE_CONSTRAINT \| (5<<8)) #define SQLITE_CONSTRAINT_PRIMARYKEY (SQLITE_CONSTRAINT \| (6<<8)) #define SQLITE_CONSTRAINT_TRIGGER (SQLITE_CONSTRAINT \| (7<<8)) #define SQLITE_CONSTRAINT_UNIQUE (SQLITE_CONSTRAINT \| (8<<8)) #define SQLITE_CONSTRAINT_VTAB (SQLITE_CONSTRAINT \| (9<<8)) #define SQLITE_CONSTRAINT_ROWID (SQLITE_CONSTRAINT \|(10<<8)) #define SQLITE_NOTICE_RECOVER_WAL (SQLITE_NOTICE \| (1<<8)) #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE \| (2<<8)) #define SQLITE_WARNING_AUTOINDEX (SQLITE_WARNING \| (1<<8)) #define SQLITE_AUTH_USER (SQLITE_AUTH \| (1<<8)) / CAPI3REF: Flags For File Open Operations These bit values are intended for use in the 3rd parameter to the [sqlite3_open_v2()] interface and ** in the 4th parameter to the [sqlite3_vfs.xOpen] method. / #define SQLITE_OPEN_READONLY 0x00000001 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_READWRITE 0x00000002 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_CREATE 0x00000004 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_DELETEONCLOSE 0x00000008 / VFS only / #define SQLITE_OPEN_EXCLUSIVE 0x00000010 / VFS only / #define SQLITE_OPEN_AUTOPROXY 0x00000020 / VFS only / #define SQLITE_OPEN_URI 0x00000040 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_MEMORY 0x00000080 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_MAIN_DB 0x00000100 / VFS only / #define SQLITE_OPEN_TEMP_DB 0x00000200 / VFS only / #define SQLITE_OPEN_TRANSIENT_DB 0x00000400 / VFS only / #define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 / VFS only / #define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 / VFS only / #define SQLITE_OPEN_SUBJOURNAL 0x00002000 / VFS only / #define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 / VFS only / #define SQLITE_OPEN_NOMUTEX 0x00008000 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_FULLMUTEX 0x00010000 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_SHAREDCACHE 0x00020000 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_PRIVATECACHE 0x00040000 / Ok for sqlite3_open_v2() / #define SQLITE_OPEN_WAL 0x00080000 / VFS only / / Reserved: 0x00F00000 / / CAPI3REF: Device Characteristics The xDeviceCharacteristics method of the [sqlite3_io_methods] object returns an integer which is a vector of these bit values expressing I/O characteristics of the mass storage device that holds the file that the [sqlite3_io_methods] refers to. The SQLITE_IOCAP_ATOMIC property means that all writes of any size are atomic. The SQLITE_IOCAP_ATOMICnnn values mean that writes of blocks that are nnn bytes in size and are aligned to an address which is an integer multiple of nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means that when data is appended to a file, the data is appended first then the size of the file is extended, never the other way around. The SQLITE_IOCAP_SEQUENTIAL property means that information is written to disk in the same order as calls to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that after reboot following a crash or power loss, the only bytes in a file that were written at the application level might have changed and that adjacent bytes, even bytes within the same sector are guaranteed to be unchanged. The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN flag indicate that a file cannot be deleted when open. The SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on read-only media and cannot be changed even by processes with elevated privileges. / #define SQLITE_IOCAP_ATOMIC 0x00000001 #define SQLITE_IOCAP_ATOMIC512 0x00000002 #define SQLITE_IOCAP_ATOMIC1K 0x00000004 #define SQLITE_IOCAP_ATOMIC2K 0x00000008 #define SQLITE_IOCAP_ATOMIC4K 0x00000010 #define SQLITE_IOCAP_ATOMIC8K 0x00000020 #define SQLITE_IOCAP_ATOMIC16K 0x00000040 #define SQLITE_IOCAP_ATOMIC32K 0x00000080 #define SQLITE_IOCAP_ATOMIC64K 0x00000100 #define SQLITE_IOCAP_SAFE_APPEND 0x00000200 #define SQLITE_IOCAP_SEQUENTIAL 0x00000400 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000 #define SQLITE_IOCAP_IMMUTABLE 0x00002000 / CAPI3REF: File Locking Levels SQLite uses one of these integer values as the second argument to calls it makes to the xLock() and xUnlock() methods ** of an [sqlite3_io_methods] object. / #define SQLITE_LOCK_NONE 0 #define SQLITE_LOCK_SHARED 1 #define SQLITE_LOCK_RESERVED 2 #define SQLITE_LOCK_PENDING 3 #define SQLITE_LOCK_EXCLUSIVE 4 / CAPI3REF: Synchronization Type Flags When SQLite invokes the xSync() method of an [sqlite3_io_methods] object it uses a combination of these integer values as the second argument. When the SQLITE_SYNC_DATAONLY flag is used, it means that the sync operation only needs to flush data to mass storage. Inode information need not be flushed. If the lower four bits of the flag equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics. If the lower four bits equal SQLITE_SYNC_FULL, that means to use Mac OS X style fullsync instead of fsync(). Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL settings. The [synchronous pragma] determines when calls to the xSync VFS method occur and applies uniformly across all platforms. The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how energetic or rigorous or forceful the sync operations are and only make a difference on Mac OSX for the default SQLite code. (Third-party VFS implementations might also make the distinction between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the operating systems natively supported by SQLite, only Mac OSX cares about the difference.) / #define SQLITE_SYNC_NORMAL 0x00002 #define SQLITE_SYNC_FULL 0x00003 #define SQLITE_SYNC_DATAONLY 0x00010 / CAPI3REF: OS Interface Open File Handle An [sqlite3_file] object represents an open file in the [sqlite3_vfs \| OS interface layer]. Individual OS interface implementations will want to subclass this object by appending additional fields for their own use. The pMethods entry is a pointer to an [sqlite3_io_methods] object that defines methods for performing ** I/O operations on the open file. / typedef struct sqlite3_file sqlite3_file; struct sqlite3_file { const struct sqlite3_io_methods pMethods; /* Methods for an open file / }; / CAPI3REF: OS Interface File Virtual Methods Object Every file opened by the [sqlite3_vfs.xOpen] method populates an [sqlite3_file] object (or, more commonly, a subclass of the [sqlite3_file] object) with a pointer to an instance of this object. This object defines the methods used to perform various operations against the open file represented by the [sqlite3_file] object. If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element to a non-NULL pointer, then the sqlite3_io_methods.xClose method may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen] is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element to NULL. The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or [SQLITE_SYNC_FULL]. The first choice is the normal fsync(). The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY] flag may be ORed in to indicate that only the data of the file and not its inode needs to be synced. The integer values to xLock() and xUnlock() are one of <ul> <li> [SQLITE_LOCK_NONE], <li> [SQLITE_LOCK_SHARED], <li> [SQLITE_LOCK_RESERVED], <li> [SQLITE_LOCK_PENDING], or <li> [SQLITE_LOCK_EXCLUSIVE]. </ul> xLock() increases the lock. xUnlock() decreases the lock. The xCheckReservedLock() method checks whether any database connection, either in this process or in some other process, is holding a RESERVED, PENDING, or EXCLUSIVE lock on the file. It returns true if such a lock exists and false otherwise. The xFileControl() method is a generic interface that allows custom VFS implementations to directly control an open file using the [sqlite3_file_control()] interface. The second "op" argument is an integer opcode. The third argument is a generic pointer intended to point to a structure that may contain arguments or space in which to write return values. Potential uses for xFileControl() might be functions to enable blocking locks with timeouts, to change the locking strategy (for example to use dot-file locks), to inquire about the status of a lock, or to break stale locks. The SQLite core reserves all opcodes less than 100 for its own use. A [file control opcodes \| list of opcodes] less than 100 is available. Applications that define a custom xFileControl method should use opcodes greater than 100 to avoid conflicts. VFS implementations should return [SQLITE_NOTFOUND] for file control opcodes that they do not recognize. The xSectorSize() method returns the sector size of the device that underlies the file. The sector size is the minimum write that can be performed without disturbing other bytes in the file. The xDeviceCharacteristics() method returns a bit vector describing behaviors of the underlying device: <ul> <li> [SQLITE_IOCAP_ATOMIC] <li> [SQLITE_IOCAP_ATOMIC512] <li> [SQLITE_IOCAP_ATOMIC1K] <li> [SQLITE_IOCAP_ATOMIC2K] <li> [SQLITE_IOCAP_ATOMIC4K] <li> [SQLITE_IOCAP_ATOMIC8K] <li> [SQLITE_IOCAP_ATOMIC16K] <li> [SQLITE_IOCAP_ATOMIC32K] <li> [SQLITE_IOCAP_ATOMIC64K] <li> [SQLITE_IOCAP_SAFE_APPEND] <li> [SQLITE_IOCAP_SEQUENTIAL] </ul> The SQLITE_IOCAP_ATOMIC property means that all writes of any size are atomic. The SQLITE_IOCAP_ATOMICnnn values mean that writes of blocks that are nnn bytes in size and are aligned to an address which is an integer multiple of nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means that when data is appended to a file, the data is appended first then the size of the file is extended, never the other way around. The SQLITE_IOCAP_SEQUENTIAL property means that information is written to disk in the same order as calls to xWrite(). If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill in the unread portions of the buffer with zeros. A VFS that fails to zero-fill short reads might seem to work. However, failure to zero-fill short reads will eventually lead to database corruption. / typedef struct sqlite3_io_methods sqlite3_io_methods; struct sqlite3_io_methods { int iVersion; int (xClose)(sqlite3_file); int (xRead)(sqlite3_file, void, int iAmt, sqlite3_int64 iOfst); int (xWrite)(sqlite3_file, const void, int iAmt, sqlite3_int64 iOfst); int (xTruncate)(sqlite3_file, sqlite3_int64 size); int (xSync)(sqlite3_file, int flags); int (xFileSize)(sqlite3_file, sqlite3_int64 pSize); int (xLock)(sqlite3_file, int); int (xUnlock)(sqlite3_file, int); int (xCheckReservedLock)(sqlite3_file, int pResOut); int (xFileControl)(sqlite3_file, int op, void pArg); int (xSectorSize)(sqlite3_file); int (xDeviceCharacteristics)(sqlite3_file); /* Methods above are valid for version 1 / int (xShmMap)(sqlite3_file, int iPg, int pgsz, int, void volatile); int (xShmLock)(sqlite3_file, int offset, int n, int flags); void (xShmBarrier)(sqlite3_file); int (xShmUnmap)(sqlite3_file, int deleteFlag); / Methods above are valid for version 2 / int (xFetch)(sqlite3_file, sqlite3_int64 iOfst, int iAmt, void pp); int (xUnfetch)(sqlite3_file, sqlite3_int64 iOfst, void p); /* Methods above are valid for version 3 / / Additional methods may be added in future releases / }; / CAPI3REF: Standard File Control Opcodes KEYWORDS: {file control opcodes} {file control opcode} These integer constants are opcodes for the xFileControl method of the [sqlite3_io_methods] object and for the [sqlite3_file_control()] interface. <ul> <li>[[SQLITE_FCNTL_LOCKSTATE]] The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This opcode causes the xFileControl method to write the current state of the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED], [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE]) into an integer that the pArg argument points to. This capability is used during testing and is only available when the SQLITE_TEST compile-time option is used. <li>[[SQLITE_FCNTL_SIZE_HINT]] The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS layer a hint of how large the database file will grow to be during the current transaction. This hint is not guaranteed to be accurate but it is often close. The underlying VFS might choose to preallocate database file space based on this hint in order to help writes to the database file run faster. <li>[[SQLITE_FCNTL_CHUNK_SIZE]] The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS extends and truncates the database file in chunks of a size specified by the user. The fourth argument to [sqlite3_file_control()] should point to an integer (type int) containing the new chunk-size to use for the nominated database. Allocating database file space in large chunks (say 1MB at a time), may reduce file-system fragmentation and improve performance on some systems. <li>[[SQLITE_FCNTL_FILE_POINTER]] The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer to the [sqlite3_file] object associated with a particular database connection. See the [sqlite3_file_control()] documentation for additional information. <li>[[SQLITE_FCNTL_SYNC_OMITTED]] No longer in use. <li>[[SQLITE_FCNTL_SYNC]] The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and sent to the VFS immediately before the xSync method is invoked on a database file descriptor. Or, if the xSync method is not invoked because the user has configured SQLite with [PRAGMA synchronous \| PRAGMA synchronous=OFF] it is invoked in place of the xSync method. In most cases, the pointer argument passed with this file-control is NULL. However, if the database file is being synced as part of a multi-database commit, the argument points to a nul-terminated string containing the transactions master-journal file name. VFSes that do not need this signal should silently ignore this opcode. Applications should not call [sqlite3_file_control()] with this opcode as doing so may disrupt the operation of the specialized VFSes that do require it. <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]] The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite and sent to the VFS after a transaction has been committed immediately but before the database is unlocked. VFSes that do not need this signal should silently ignore this opcode. Applications should not call [sqlite3_file_control()] with this opcode as doing so may disrupt the operation of the specialized VFSes that do require it. <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]] ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic retry counts and intervals for certain disk I/O operations for the windows [VFS] in order to provide robustness in the presence of anti-virus programs. By default, the windows VFS will retry file read, file write, and file delete operations up to 10 times, with a delay of 25 milliseconds before the first retry and with the delay increasing by an additional 25 milliseconds with each subsequent retry. This opcode allows these two values (10 retries and 25 milliseconds of delay) to be adjusted. The values are changed for all database connections within the same process. The argument is a pointer to an array of two integers where the first integer i the new retry count and the second integer is the delay. If either integer is negative, then the setting is not changed but instead the prior value of that setting is written into the array entry, allowing the current retry settings to be interrogated. The zDbName parameter is ignored. <li>[[SQLITE_FCNTL_PERSIST_WAL]] ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the persistent [WAL \| Write Ahead Log] setting. By default, the auxiliary write ahead log and shared memory files used for transaction control are automatically deleted when the latest connection to the database closes. Setting persistent WAL mode causes those files to persist after close. Persisting the files is useful when other processes that do not have write permission on the directory containing the database file want to read the database file, as the WAL and shared memory files must exist in order for the database to be readable. The fourth parameter to [sqlite3_file_control()] for this opcode should be a pointer to an integer. That integer is 0 to disable persistent WAL mode or 1 to enable persistent WAL mode. If the integer is -1, then it is overwritten with the current WAL persistence setting. <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]] ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the xDeviceCharacteristics methods. The fourth parameter to [sqlite3_file_control()] for this opcode should be a pointer to an integer. That integer is 0 to disable zero-damage mode or 1 to enable zero-damage mode. If the integer is -1, then it is overwritten with the current zero-damage mode setting. <li>[[SQLITE_FCNTL_OVERWRITE]] ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening a write transaction to indicate that, unless it is rolled back for some reason, the entire database file will be overwritten by the current transaction. This is used by VACUUM operations. <li>[[SQLITE_FCNTL_VFSNAME]] ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of all [VFSes] in the VFS stack. The names are of all VFS shims and the final bottom-level VFS are written into memory obtained from [sqlite3_malloc()] and the result is stored in the char* variable that the fourth parameter of [sqlite3_file_control()] points to. The caller is responsible for freeing the memory when done. As with all file-control actions, there is no guarantee that this will actually do anything. Callers should initialize the char* variable to a NULL pointer in case this file-control is not implemented. This file-control is intended for diagnostic use only. <li>[[SQLITE_FCNTL_PRAGMA]] ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] file control is sent to the open [sqlite3_file] object corresponding to the database file to which the pragma statement refers. ^The argument to the [SQLITE_FCNTL_PRAGMA] file control is an array of pointers to strings (char) in which the second element of the array is the name of the pragma and the third element is the argument to the pragma or NULL if the pragma has no argument. ^The handler for an [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element of the char argument point to a string obtained from [sqlite3_mprintf()] or the equivalent and that string will become the result of the pragma or the error message if the pragma fails. ^If the [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal [PRAGMA] processing continues. ^If the [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_OK], then the parser assumes that the VFS has handled the PRAGMA itself and the parser generates a no-op prepared statement if result string is NULL, or that returns a copy of the result string if the string is non-NULL. ^If the [SQLITE_FCNTL_PRAGMA] file control returns any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means that the VFS encountered an error while handling the [PRAGMA] and the compilation of the PRAGMA fails with an error. ^The [SQLITE_FCNTL_PRAGMA] file control occurs at the beginning of pragma statement analysis and so it is able to override built-in [PRAGMA] statements. <li>[[SQLITE_FCNTL_BUSYHANDLER]] ^The [SQLITE_FCNTL_BUSYHANDLER] file-control may be invoked by SQLite on the database file handle shortly after it is opened in order to provide a custom VFS with access to the connections busy-handler callback. The argument is of type (void ) ** - an array of two (void ) values. The first (void ) actually points ** to a function of type (int ()(void )). In order to invoke the connections ** busy-handler, this function should be invoked with the second (void ) in * the array as the only argument. If it returns non-zero, then the operation should be retried. If it returns zero, the custom VFS should abandon the current operation. <li>[[SQLITE_FCNTL_TEMPFILENAME]] ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control to have SQLite generate a temporary filename using the same algorithm that is followed to generate temporary filenames for TEMP tables and other internal uses. The argument should be a char which will be filled with the filename written into memory obtained from [sqlite3_malloc()]. The caller should invoke [sqlite3_free()] on the result to avoid a memory leak. <li>[[SQLITE_FCNTL_MMAP_SIZE]] The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the maximum number of bytes that will be used for memory-mapped I/O. The argument is a pointer to a value of type sqlite3_int64 that is an advisory maximum number of bytes in the file to memory map. The pointer is overwritten with the old value. The limit is not changed if the value originally pointed to is negative, and so the current limit can be queried by passing in a pointer to a negative number. This file-control is used internally to implement [PRAGMA mmap_size]. <li>[[SQLITE_FCNTL_TRACE]] The [SQLITE_FCNTL_TRACE] file control provides advisory information to the VFS about what the higher layers of the SQLite stack are doing. This file control is used by some VFS activity tracing [shims]. The argument is a zero-terminated string. Higher layers in the SQLite stack may generate instances of this file control if the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled. <li>[[SQLITE_FCNTL_HAS_MOVED]] The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a pointer to an integer and it writes a boolean into that integer depending on whether or not the file has been renamed, moved, or deleted since it was first opened. <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]] The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging. This opcode causes the xFileControl method to swap the file handle with the one pointed to by the pArg argument. This capability is used during testing and only needs to be supported when SQLITE_TEST is defined. <li>[[SQLITE_FCNTL_WAL_BLOCK]] The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might be advantageous to block on the next WAL lock if the lock is not immediately available. The WAL subsystem issues this signal during rare circumstances in order to fix a problem with priority inversion. Applications should <em>not</em> use this file-control. ** </ul> / #define SQLITE_FCNTL_LOCKSTATE 1 #define SQLITE_FCNTL_GET_LOCKPROXYFILE 2 #define SQLITE_FCNTL_SET_LOCKPROXYFILE 3 #define SQLITE_FCNTL_LAST_ERRNO 4 #define SQLITE_FCNTL_SIZE_HINT 5 #define SQLITE_FCNTL_CHUNK_SIZE 6 #define SQLITE_FCNTL_FILE_POINTER 7 #define SQLITE_FCNTL_SYNC_OMITTED 8 #define SQLITE_FCNTL_WIN32_AV_RETRY 9 #define SQLITE_FCNTL_PERSIST_WAL 10 #define SQLITE_FCNTL_OVERWRITE 11 #define SQLITE_FCNTL_VFSNAME 12 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE 13 #define SQLITE_FCNTL_PRAGMA 14 #define SQLITE_FCNTL_BUSYHANDLER 15 #define SQLITE_FCNTL_TEMPFILENAME 16 #define SQLITE_FCNTL_MMAP_SIZE 18 #define SQLITE_FCNTL_TRACE 19 #define SQLITE_FCNTL_HAS_MOVED 20 #define SQLITE_FCNTL_SYNC 21 #define SQLITE_FCNTL_COMMIT_PHASETWO 22 #define SQLITE_FCNTL_WIN32_SET_HANDLE 23 #define SQLITE_FCNTL_WAL_BLOCK 24 / deprecated names / #define SQLITE_GET_LOCKPROXYFILE SQLITE_FCNTL_GET_LOCKPROXYFILE #define SQLITE_SET_LOCKPROXYFILE SQLITE_FCNTL_SET_LOCKPROXYFILE #define SQLITE_LAST_ERRNO SQLITE_FCNTL_LAST_ERRNO / CAPI3REF: Mutex Handle The mutex module within SQLite defines [sqlite3_mutex] to be an abstract type for a mutex object. The SQLite core never looks at the internal representation of an [sqlite3_mutex]. It only deals with pointers to the [sqlite3_mutex] object. Mutexes are created using [sqlite3_mutex_alloc()]. / typedef struct sqlite3_mutex sqlite3_mutex; / CAPI3REF: OS Interface Object An instance of the sqlite3_vfs object defines the interface between the SQLite core and the underlying operating system. The "vfs" in the name of the object stands for "virtual file system". See the [VFS \| VFS documentation] for further information. The value of the iVersion field is initially 1 but may be larger in future versions of SQLite. Additional fields may be appended to this object when the iVersion value is increased. Note that the structure of the sqlite3_vfs object changes in the transaction between SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not modified. The szOsFile field is the size of the subclassed [sqlite3_file] structure used by this VFS. mxPathname is the maximum length of a pathname in this VFS. Registered sqlite3_vfs objects are kept on a linked list formed by the pNext pointer. The [sqlite3_vfs_register()] and [sqlite3_vfs_unregister()] interfaces manage this list in a thread-safe way. The [sqlite3_vfs_find()] interface searches the list. Neither the application code nor the VFS implementation should use the pNext pointer. The pNext field is the only field in the sqlite3_vfs structure that SQLite will ever modify. SQLite will only access or modify this field while holding a particular static mutex. The application should never modify anything within the sqlite3_vfs object once the object has been registered. The zName field holds the name of the VFS module. The name must be unique across all VFS modules. [[sqlite3_vfs.xOpen]] ^SQLite guarantees that the zFilename parameter to xOpen is either a NULL pointer or string obtained from xFullPathname() with an optional suffix added. ^If a suffix is added to the zFilename parameter, it will consist of a single "-" character followed by no more than 11 alphanumeric and/or "-" characters. ^SQLite further guarantees that the string will be valid and unchanged until xClose() is called. Because of the previous sentence, the [sqlite3_file] can safely store a pointer to the filename if it needs to remember the filename for some reason. If the zFilename parameter to xOpen is a NULL pointer then xOpen must invent its own temporary name for the file. ^Whenever the xFilename parameter is NULL it will also be the case that the flags parameter will include [SQLITE_OPEN_DELETEONCLOSE]. The flags argument to xOpen() includes all bits set in the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()] or [sqlite3_open16()] is used, then flags includes at least [SQLITE_OPEN_READWRITE] \| [SQLITE_OPEN_CREATE]. If xOpen() opens a file read-only then it sets pOutFlags to * include [SQLITE_OPEN_READONLY]. Other bits in pOutFlags may be set. * ^(SQLite will also add one of the following flags to the xOpen() call, depending on the object being opened: <ul> <li> [SQLITE_OPEN_MAIN_DB] <li> [SQLITE_OPEN_MAIN_JOURNAL] <li> [SQLITE_OPEN_TEMP_DB] <li> [SQLITE_OPEN_TEMP_JOURNAL] <li> [SQLITE_OPEN_TRANSIENT_DB] <li> [SQLITE_OPEN_SUBJOURNAL] <li> [SQLITE_OPEN_MASTER_JOURNAL] <li> [SQLITE_OPEN_WAL] </ul>)^ The file I/O implementation can use the object type flags to change the way it deals with files. For example, an application that does not care about crash recovery or rollback might make the open of a journal file a no-op. Writes to this journal would also be no-ops, and any attempt to read the journal would return SQLITE_IOERR. Or the implementation might recognize that a database file will be doing page-aligned sector reads and writes in a random order and set up its I/O subsystem accordingly. SQLite might also add one of the following flags to the xOpen method: <ul> <li> [SQLITE_OPEN_DELETEONCLOSE] <li> [SQLITE_OPEN_EXCLUSIVE] </ul> The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE] will be set for TEMP databases and their journals, transient databases, and subjournals. ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction with the [SQLITE_OPEN_CREATE] flag, which are both directly analogous to the O_EXCL and O_CREAT flags of the POSIX open() API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the SQLITE_OPEN_CREATE, is used to indicate that file should always be created, and that it is an error if it already exists. It is <i>not</i> used to indicate the file should be opened for exclusive access. ^At least szOsFile bytes of memory are allocated by SQLite to hold the [sqlite3_file] structure passed as the third argument to xOpen. The xOpen method does not have to allocate the structure; it should just fill it in. Note that the xOpen method must set the sqlite3_file.pMethods to either a valid [sqlite3_io_methods] object or to NULL. xOpen must do this even if the open fails. SQLite expects that the sqlite3_file.pMethods element will be valid after xOpen returns regardless of the success or failure of the xOpen call. [[sqlite3_vfs.xAccess]] ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS] to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to test whether a file is readable and writable, or [SQLITE_ACCESS_READ] to test whether a file is at least readable. The file can be a directory. ^SQLite will always allocate at least mxPathname+1 bytes for the output buffer xFullPathname. The exact size of the output buffer is also passed as a parameter to both methods. If the output buffer is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is handled as a fatal error by SQLite, vfs implementations should endeavor to prevent this by setting mxPathname to a sufficiently large value. The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64() interfaces are not strictly a part of the filesystem, but they are included in the VFS structure for completeness. The xRandomness() function attempts to return nBytes bytes of good-quality randomness into zOut. The return value is the actual number of bytes of randomness obtained. The xSleep() method causes the calling thread to sleep for at least the number of microseconds given. ^The xCurrentTime() method returns a Julian Day Number for the current date and time as a floating point value. ^The xCurrentTimeInt64() method returns, as an integer, the Julian Day Number multiplied by 86400000 (the number of milliseconds in a 24-hour day). ^SQLite will use the xCurrentTimeInt64() method to get the current date and time if that method is available (if iVersion is 2 or greater and the function pointer is not NULL) and will fall back to xCurrentTime() if xCurrentTimeInt64() is unavailable. ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces are not used by the SQLite core. These optional interfaces are provided by some VFSes to facilitate testing of the VFS code. By overriding system calls with functions under its control, a test program can simulate faults and error conditions that would otherwise be difficult or impossible to induce. The set of system calls that can be overridden varies from one VFS to another, and from one version of the same VFS to the next. Applications that use these interfaces must be prepared for any or all of these interfaces to be NULL or for their behavior to change from one release to the next. Applications must not attempt to access ** any of these methods if the iVersion of the VFS is less than 3. / typedef struct sqlite3_vfs sqlite3_vfs; typedef void (sqlite3_syscall_ptr)(void); struct sqlite3_vfs { int iVersion; /* Structure version number (currently 3) / int szOsFile; / Size of subclassed sqlite3_file / int mxPathname; / Maximum file pathname length / sqlite3_vfs pNext; /* Next registered VFS / const char zName; /* Name of this virtual file system / void pAppData; /* Pointer to application-specific data / int (xOpen)(sqlite3_vfs, const char zName, sqlite3_file, int flags, int pOutFlags); int (xDelete)(sqlite3_vfs, const char zName, int syncDir); int (xAccess)(sqlite3_vfs, const char zName, int flags, int pResOut); int (xFullPathname)(sqlite3_vfs, const char zName, int nOut, char zOut); void (xDlOpen)(sqlite3_vfs, const char zFilename); void (xDlError)(sqlite3_vfs, int nByte, char zErrMsg); void ((xDlSym)(sqlite3_vfs,void, const char zSymbol))(void); void (xDlClose)(sqlite3_vfs, void); int (xRandomness)(sqlite3_vfs, int nByte, char zOut); int (xSleep)(sqlite3_vfs, int microseconds); int (xCurrentTime)(sqlite3_vfs, double); int (xGetLastError)(sqlite3_vfs, int, char ); / The methods above are in version 1 of the sqlite_vfs object definition. Those that follow are added in version 2 or later / int (xCurrentTimeInt64)(sqlite3_vfs, sqlite3_int64); /* The methods above are in versions 1 and 2 of the sqlite_vfs object. Those below are for version 3 and greater. / int (xSetSystemCall)(sqlite3_vfs, const char zName, sqlite3_syscall_ptr); sqlite3_syscall_ptr (xGetSystemCall)(sqlite3_vfs, const char zName); const char (xNextSystemCall)(sqlite3_vfs, const char zName); / The methods above are in versions 1 through 3 of the sqlite_vfs object. New fields may be appended in figure versions. The iVersion ** value will increment whenever this happens. / }; / CAPI3REF: Flags for the xAccess VFS method These integer constants can be used as the third parameter to the xAccess method of an [sqlite3_vfs] object. They determine what kind of permissions the xAccess method is looking for. With SQLITE_ACCESS_EXISTS, the xAccess method simply checks whether the file exists. With SQLITE_ACCESS_READWRITE, the xAccess method checks whether the named directory is both readable and writable (in other words, if files can be added, removed, and renamed within the directory). The SQLITE_ACCESS_READWRITE constant is currently used only by the [temp_store_directory pragma], though this could change in a future release of SQLite. With SQLITE_ACCESS_READ, the xAccess method checks whether the file is readable. The SQLITE_ACCESS_READ constant is currently unused, though it might be used in a future release of SQLite. / #define SQLITE_ACCESS_EXISTS 0 #define SQLITE_ACCESS_READWRITE 1 / Used by PRAGMA temp_store_directory / #define SQLITE_ACCESS_READ 2 / Unused / / CAPI3REF: Flags for the xShmLock VFS method These integer constants define the various locking operations allowed by the xShmLock method of [sqlite3_io_methods]. The following are the only legal combinations of flags to the xShmLock method: <ul> <li> SQLITE_SHM_LOCK \| SQLITE_SHM_SHARED <li> SQLITE_SHM_LOCK \| SQLITE_SHM_EXCLUSIVE <li> SQLITE_SHM_UNLOCK \| SQLITE_SHM_SHARED <li> SQLITE_SHM_UNLOCK \| SQLITE_SHM_EXCLUSIVE </ul> When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as was given on the corresponding lock. The xShmLock method can transition between unlocked and SHARED or between unlocked and EXCLUSIVE. It cannot transition between SHARED and EXCLUSIVE. / #define SQLITE_SHM_UNLOCK 1 #define SQLITE_SHM_LOCK 2 #define SQLITE_SHM_SHARED 4 #define SQLITE_SHM_EXCLUSIVE 8 / CAPI3REF: Maximum xShmLock index The xShmLock method on [sqlite3_io_methods] may use values between 0 and this upper bound as its "offset" argument. The SQLite core will never attempt to acquire or release a lock outside of this range / #define SQLITE_SHM_NLOCK 8 / CAPI3REF: Initialize The SQLite Library ^The sqlite3_initialize() routine initializes the SQLite library. ^The sqlite3_shutdown() routine deallocates any resources that were allocated by sqlite3_initialize(). These routines are designed to aid in process initialization and shutdown on embedded systems. Workstation applications using SQLite normally do not need to invoke either of these routines. A call to sqlite3_initialize() is an "effective" call if it is the first time sqlite3_initialize() is invoked during the lifetime of the process, or if it is the first time sqlite3_initialize() is invoked following a call to sqlite3_shutdown(). ^(Only an effective call of sqlite3_initialize() does any initialization. All other calls are harmless no-ops.)^ A call to sqlite3_shutdown() is an "effective" call if it is the first call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only an effective call to sqlite3_shutdown() does any deinitialization. All other valid calls to sqlite3_shutdown() are harmless no-ops.)^ The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown() is not. The sqlite3_shutdown() interface must only be called from a single thread. All open [database connections] must be closed and all other SQLite resources must be deallocated prior to invoking sqlite3_shutdown(). Among other things, ^sqlite3_initialize() will invoke sqlite3_os_init(). Similarly, ^sqlite3_shutdown() will invoke sqlite3_os_end(). ^The sqlite3_initialize() routine returns [SQLITE_OK] on success. ^If for some reason, sqlite3_initialize() is unable to initialize the library (perhaps it is unable to allocate a needed resource such as a mutex) it returns an [error code] other than [SQLITE_OK]. ^The sqlite3_initialize() routine is called internally by many other SQLite interfaces so that an application usually does not need to invoke sqlite3_initialize() directly. For example, [sqlite3_open()] calls sqlite3_initialize() so the SQLite library will be automatically initialized when [sqlite3_open()] is called if it has not be initialized already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT] compile-time option, then the automatic calls to sqlite3_initialize() are omitted and the application must call sqlite3_initialize() directly prior to using any other SQLite interface. For maximum portability, it is recommended that applications always invoke sqlite3_initialize() directly prior to using any other SQLite interface. Future releases of SQLite may require this. In other words, the behavior exhibited when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the default behavior in some future release of SQLite. The sqlite3_os_init() routine does operating-system specific initialization of the SQLite library. The sqlite3_os_end() routine undoes the effect of sqlite3_os_init(). Typical tasks performed by these routines include allocation or deallocation of static resources, initialization of global variables, setting up a default [sqlite3_vfs] module, or setting up a default configuration using [sqlite3_config()]. The application should never invoke either sqlite3_os_init() or sqlite3_os_end() directly. The application should only invoke sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init() interface is called automatically by sqlite3_initialize() and sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate implementations for sqlite3_os_init() and sqlite3_os_end() are built into SQLite when it is compiled for Unix, Windows, or OS/2. When [custom builds \| built for other platforms] (using the [SQLITE_OS_OTHER=1] compile-time option) the application must supply a suitable implementation for sqlite3_os_init() and sqlite3_os_end(). An application-supplied implementation of sqlite3_os_init() or sqlite3_os_end() must return [SQLITE_OK] on success and some other [error code] upon ** failure. / SQLITE_API int SQLITE_STDCALL sqlite3_initialize(void); SQLITE_API int SQLITE_STDCALL sqlite3_shutdown(void); SQLITE_API int SQLITE_STDCALL sqlite3_os_init(void); SQLITE_API int SQLITE_STDCALL sqlite3_os_end(void); / CAPI3REF: Configuring The SQLite Library The sqlite3_config() interface is used to make global configuration changes to SQLite in order to tune SQLite to the specific needs of the application. The default configuration is recommended for most applications and so this routine is usually not necessary. It is provided to support rare applications with unusual needs. The sqlite3_config() interface is not threadsafe. The application must insure that no other SQLite interfaces are invoked by other threads while sqlite3_config() is running. Furthermore, sqlite3_config() may only be invoked prior to library initialization using [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()]. ^If sqlite3_config() is called after [sqlite3_initialize()] and before [sqlite3_shutdown()] then it will return SQLITE_MISUSE. Note, however, that ^sqlite3_config() can be called as part of the implementation of an application-defined [sqlite3_os_init()]. The first argument to sqlite3_config() is an integer [configuration option] that determines what property of SQLite is to be configured. Subsequent arguments vary depending on the [configuration option] in the first argument. ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK]. ^If the option is unknown or SQLite is unable to set the option ** then this routine returns a non-zero [error code]. / SQLITE_API int SQLITE_CDECL sqlite3_config(int, ...); / CAPI3REF: Configure database connections METHOD: sqlite3 The sqlite3_db_config() interface is used to make configuration changes to a [database connection]. The interface is similar to [sqlite3_config()] except that the changes apply to a single [database connection] (specified in the first argument). The second argument to sqlite3_db_config(D,V,...) is the [SQLITE_DBCONFIG_LOOKASIDE \| configuration verb] - an integer code that indicates what aspect of the [database connection] is being configured. Subsequent arguments vary depending on the configuration verb. ^Calls to sqlite3_db_config() return SQLITE_OK if and only if ** the call is considered successful. / SQLITE_API int SQLITE_CDECL sqlite3_db_config(sqlite3, int op, ...); /* CAPI3REF: Memory Allocation Routines An instance of this object defines the interface between SQLite and low-level memory allocation routines. This object is used in only one place in the SQLite interface. A pointer to an instance of this object is the argument to [sqlite3_config()] when the configuration option is [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC]. By creating an instance of this object and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC]) during configuration, an application can specify an alternative memory allocation subsystem for SQLite to use for all of its dynamic memory needs. Note that SQLite comes with several [built-in memory allocators] that are perfectly adequate for the overwhelming majority of applications and that this object is only useful to a tiny minority of applications with specialized memory allocation requirements. This object is also used during testing of SQLite in order to specify an alternative memory allocator that simulates memory out-of-memory conditions in order to verify that SQLite recovers gracefully from such conditions. The xMalloc, xRealloc, and xFree methods must work like the malloc(), realloc() and free() functions from the standard C library. ^SQLite guarantees that the second argument to xRealloc is always a value returned by a prior call to xRoundup. xSize should return the allocated size of a memory allocation previously obtained from xMalloc or xRealloc. The allocated size is always at least as big as the requested size but may be larger. The xRoundup method returns what would be the allocated size of a memory allocation given a particular requested size. Most memory allocators round up memory allocations at least to the next multiple of 8. Some allocators round up to a larger multiple or to a power of 2. Every memory allocation request coming in through [sqlite3_malloc()] or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0, that causes the corresponding memory allocation to fail. The xInit method initializes the memory allocator. For example, it might allocate any require mutexes or initialize internal data structures. The xShutdown method is invoked (indirectly) by [sqlite3_shutdown()] and should deallocate any resources acquired by xInit. The pAppData pointer is used as the only parameter to xInit and xShutdown. SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes the xInit method, so the xInit method need not be threadsafe. The xShutdown method is only called from [sqlite3_shutdown()] so it does not need to be threadsafe either. For all other methods, SQLite holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which it is by default) and so the methods are automatically serialized. However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other methods must be threadsafe or else make their own arrangements for serialization. SQLite will never invoke xInit() more than once without an intervening ** call to xShutdown(). / typedef struct sqlite3_mem_methods sqlite3_mem_methods; struct sqlite3_mem_methods { void (xMalloc)(int); / Memory allocation function / void (xFree)(void); / Free a prior allocation / void (xRealloc)(void,int); /* Resize an allocation / int (xSize)(void); / Return the size of an allocation / int (xRoundup)(int); /* Round up request size to allocation size / int (xInit)(void); / Initialize the memory allocator / void (xShutdown)(void); / Deinitialize the memory allocator / void pAppData; /* Argument to xInit() and xShutdown() / }; / CAPI3REF: Configuration Options KEYWORDS: {configuration option} These constants are the available integer configuration options that can be passed as the first argument to the [sqlite3_config()] interface. New configuration options may be added in future releases of SQLite. Existing configuration options might be discontinued. Applications should check the return code from [sqlite3_config()] to make sure that the call worked. The [sqlite3_config()] interface will return a non-zero [error code] if a discontinued or unsupported configuration option is invoked. <dl> [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt> <dd>There are no arguments to this option. ^This option sets the [threading mode] to Single-thread. In other words, it disables all mutexing and puts SQLite into a mode where it can only be used by a single thread. ^If SQLite is compiled with the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then it is not possible to change the [threading mode] from its default value of Single-thread and so [sqlite3_config()] will return [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD configuration option.</dd> [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt> <dd>There are no arguments to this option. ^This option sets the [threading mode] to Multi-thread. In other words, it disables mutexing on [database connection] and [prepared statement] objects. The application is responsible for serializing access to [database connections] and [prepared statements]. But other mutexes are enabled so that SQLite will be safe to use in a multi-threaded environment as long as no two threads attempt to use the same [database connection] at the same time. ^If SQLite is compiled with the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then it is not possible to set the Multi-thread [threading mode] and [sqlite3_config()] will return [SQLITE_ERROR] if called with the SQLITE_CONFIG_MULTITHREAD configuration option.</dd> [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt> <dd>There are no arguments to this option. ^This option sets the [threading mode] to Serialized. In other words, this option enables all mutexes including the recursive mutexes on [database connection] and [prepared statement] objects. In this mode (which is the default when SQLite is compiled with [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access to [database connections] and [prepared statements] so that the application is free to use the same [database connection] or the same [prepared statement] in different threads at the same time. ^If SQLite is compiled with the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then it is not possible to set the Serialized [threading mode] and [sqlite3_config()] will return [SQLITE_ERROR] if called with the SQLITE_CONFIG_SERIALIZED configuration option.</dd> [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt> <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is a pointer to an instance of the [sqlite3_mem_methods] structure. The argument specifies alternative low-level memory allocation routines to be used in place of the memory allocation routines built into SQLite.)^ ^SQLite makes its own private copy of the content of the [sqlite3_mem_methods] structure before the [sqlite3_config()] call returns.</dd> [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt> <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which is a pointer to an instance of the [sqlite3_mem_methods] structure. The [sqlite3_mem_methods] structure is filled with the currently defined memory allocation routines.)^ This option can be used to overload the default memory allocation routines with a wrapper that simulations memory allocation failure or tracks memory usage, for example. </dd> [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt> <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int, interpreted as a boolean, which enables or disables the collection of memory allocation statistics. ^(When memory allocation statistics are disabled, the following SQLite interfaces become non-operational: <ul> <li> [sqlite3_memory_used()] <li> [sqlite3_memory_highwater()] <li> [sqlite3_soft_heap_limit64()] <li> [sqlite3_status64()] </ul>)^ ^Memory allocation statistics are enabled by default unless SQLite is compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory allocation statistics are disabled by default. </dd> [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt> <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer that SQLite can use for scratch memory. ^(There are three arguments to SQLITE_CONFIG_SCRATCH: A pointer an 8-byte aligned memory buffer from which the scratch allocations will be drawn, the size of each scratch allocation (sz), and the maximum number of scratch allocations (N).)^ The first argument must be a pointer to an 8-byte aligned buffer of at least szN bytes of memory. * ^SQLite will not use more than one scratch buffers per thread. ^SQLite will never request a scratch buffer that is more than 6 times the database page size. ^If SQLite needs needs additional scratch memory beyond what is provided by this configuration option, then [sqlite3_malloc()] will be used to obtain the memory needed.<p> ^When the application provides any amount of scratch memory using SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large [sqlite3_malloc\|heap allocations]. This can help [Robson proof\|prevent memory allocation failures] due to heap fragmentation in low-memory embedded systems. </dd> [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt> <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a static memory buffer that SQLite can use for the database page cache with the default page cache implementation. This configuration should not be used if an application-define page cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2] configuration option. ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned memory, the size of each page buffer (sz), and the number of pages (N). The sz argument should be the size of the largest database page (a power of two between 512 and 65536) plus some extra bytes for each page header. ^The number of extra bytes needed by the page header can be determined using the [SQLITE_CONFIG_PCACHE_HDRSZ] option to [sqlite3_config()]. ^It is harmless, apart from the wasted memory, for the sz parameter to be larger than necessary. The first argument should pointer to an 8-byte aligned block of memory that ** is at least szN bytes of memory, otherwise subsequent behavior is * undefined. ^SQLite will use the memory provided by the first argument to satisfy its memory needs for the first N pages that it adds to cache. ^If additional page cache memory is needed beyond what is provided by this option, then SQLite goes to [sqlite3_malloc()] for the additional storage space.</dd> [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt> <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer that SQLite will use for all of its dynamic memory allocation needs beyond those provided for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE]. ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns [SQLITE_ERROR] if invoked otherwise. ^There are three arguments to SQLITE_CONFIG_HEAP: An 8-byte aligned pointer to the memory, the number of bytes in the memory buffer, and the minimum allocation size. ^If the first pointer (the memory pointer) is NULL, then SQLite reverts to using its default memory allocator (the system malloc() implementation), undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the memory pointer is not NULL then the alternative memory allocator is engaged to handle all of SQLites memory allocation needs. The first pointer (the memory pointer) must be aligned to an 8-byte boundary or subsequent behavior of SQLite will be undefined. The minimum allocation size is capped at 212. Reasonable values for the minimum allocation size are 25 through 28.</dd> [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt> <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a pointer to an instance of the [sqlite3_mutex_methods] structure. The argument specifies alternative low-level mutex routines to be used in place the mutex routines built into SQLite.)^ ^SQLite makes a copy of the content of the [sqlite3_mutex_methods] structure before the call to [sqlite3_config()] returns. ^If SQLite is compiled with the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then the entire mutexing subsystem is omitted from the build and hence calls to [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will return [SQLITE_ERROR].</dd> [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt> <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which is a pointer to an instance of the [sqlite3_mutex_methods] structure. The [sqlite3_mutex_methods] structure is filled with the currently defined mutex routines.)^ This option can be used to overload the default mutex allocation routines with a wrapper used to track mutex usage for performance profiling or testing, for example. ^If SQLite is compiled with the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then the entire mutexing subsystem is omitted from the build and hence calls to [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will return [SQLITE_ERROR].</dd> [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt> <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine the default size of lookaside memory on each [database connection]. The first argument is the size of each lookaside buffer slot and the second is the number of slots allocated to each database connection.)^ ^(SQLITE_CONFIG_LOOKASIDE sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE] option to [sqlite3_db_config()] can be used to change the lookaside configuration on individual connections.)^ </dd> [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt> <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is a pointer to an [sqlite3_pcache_methods2] object. This object specifies the interface to a custom page cache implementation.)^ ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd> [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt> <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which is a pointer to an [sqlite3_pcache_methods2] object. SQLite copies of the current page cache implementation into that object.)^ </dd> [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt> <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite global [error log]. (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a function with a call signature of void()(void,int,const char), * and a pointer to void. ^If the function pointer is not NULL, it is invoked by [sqlite3_log()] to process each logging event. ^If the function pointer is NULL, the [sqlite3_log()] interface becomes a no-op. ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is passed through as the first parameter to the application-defined logger function whenever that function is invoked. ^The second parameter to the logger function is a copy of the first parameter to the corresponding [sqlite3_log()] call and is intended to be a [result code] or an [extended result code]. ^The third parameter passed to the logger is log message after formatting via [sqlite3_snprintf()]. The SQLite logging interface is not reentrant; the logger function supplied by the application must not invoke any SQLite interface. In a multi-threaded application, the application-defined logger function must be threadsafe. </dd> [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int. If non-zero, then URI handling is globally enabled. If the parameter is zero, then URI handling is globally disabled.)^ ^If URI handling is globally enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or specified as part of [ATTACH] commands are interpreted as URIs, regardless of whether or not the [SQLITE_OPEN_URI] flag is set when the database connection is opened. ^If it is globally disabled, filenames are only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the database connection is opened. ^(By default, URI handling is globally disabled. The default value may be changed by compiling with the [SQLITE_USE_URI] symbol defined.)^ [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer argument which is interpreted as a boolean in order to enable or disable the use of covering indices for full table scans in the query optimizer. ^The default setting is determined by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on" if that compile-time option is omitted. The ability to disable the use of covering indices for full table scans is because some incorrectly coded legacy applications might malfunction when the optimization is enabled. Providing the ability to disable the optimization allows the older, buggy application code to work without change even with newer versions of SQLite. [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]] <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE <dd> These options are obsolete and should not be used by new code. They are retained for backwards compatibility but are now no-ops. </dd> [[SQLITE_CONFIG_SQLLOG]] <dt>SQLITE_CONFIG_SQLLOG <dd>This option is only available if sqlite is compiled with the [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should be a pointer to a function of type void()(void,sqlite3,const char, int). ** The second should be of type (void). The callback is invoked by the library * in three separate circumstances, identified by the value passed as the fourth parameter. If the fourth parameter is 0, then the database connection passed as the second argument has just been opened. The third argument points to a buffer containing the name of the main database file. If the fourth parameter is 1, then the SQL statement that the third parameter points to has just been executed. Or, if the fourth parameter is 2, then the connection being passed as the second parameter is being closed. The third parameter is passed NULL In this case. An example of using this configuration option can be seen in the "test_sqllog.c" source file in the canonical SQLite source tree.</dd> [[SQLITE_CONFIG_MMAP_SIZE]] <dt>SQLITE_CONFIG_MMAP_SIZE <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values that are the default mmap size limit (the default setting for [PRAGMA mmap_size]) and the maximum allowed mmap size limit. ^The default setting can be overridden by each database connection using either the [PRAGMA mmap_size] command, or by using the [SQLITE_FCNTL_MMAP_SIZE] file control. ^(The maximum allowed mmap size will be silently truncated if necessary so that it does not exceed the compile-time maximum mmap size set by the [SQLITE_MAX_MMAP_SIZE] compile-time option.)^ ^If either argument to this option is negative, then that argument is changed to its compile-time default. [[SQLITE_CONFIG_WIN32_HEAPSIZE]] <dt>SQLITE_CONFIG_WIN32_HEAPSIZE <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value that specifies the maximum size of the created heap. [[SQLITE_CONFIG_PCACHE_HDRSZ]] <dt>SQLITE_CONFIG_PCACHE_HDRSZ <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which is a pointer to an integer and writes into that integer the number of extra bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE]. The amount of extra space required can change depending on the compiler, target platform, and SQLite version. [[SQLITE_CONFIG_PMASZ]] <dt>SQLITE_CONFIG_PMASZ <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded sorter to that integer. The default minimum PMA Size is set by the [SQLITE_SORTER_PMASZ] compile-time option. New threads are launched to help with sort operations when multithreaded sorting is enabled (using the [PRAGMA threads] command) and the amount of content to be sorted exceeds the page size times the minimum of the [PRAGMA cache_size] setting and this value. </dl> / #define SQLITE_CONFIG_SINGLETHREAD 1 / nil / #define SQLITE_CONFIG_MULTITHREAD 2 / nil / #define SQLITE_CONFIG_SERIALIZED 3 / nil / #define SQLITE_CONFIG_MALLOC 4 / sqlite3_mem_methods* / #define SQLITE_CONFIG_GETMALLOC 5 / sqlite3_mem_methods* / #define SQLITE_CONFIG_SCRATCH 6 / void, int sz, int N / #define SQLITE_CONFIG_PAGECACHE 7 /* void, int sz, int N / #define SQLITE_CONFIG_HEAP 8 /* void, int nByte, int min / #define SQLITE_CONFIG_MEMSTATUS 9 /* boolean / #define SQLITE_CONFIG_MUTEX 10 / sqlite3_mutex_methods* / #define SQLITE_CONFIG_GETMUTEX 11 / sqlite3_mutex_methods* / / previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. / #define SQLITE_CONFIG_LOOKASIDE 13 / int int / #define SQLITE_CONFIG_PCACHE 14 / no-op / #define SQLITE_CONFIG_GETPCACHE 15 / no-op / #define SQLITE_CONFIG_LOG 16 / xFunc, void* / #define SQLITE_CONFIG_URI 17 / int / #define SQLITE_CONFIG_PCACHE2 18 / sqlite3_pcache_methods2* / #define SQLITE_CONFIG_GETPCACHE2 19 / sqlite3_pcache_methods2* / #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20 / int / #define SQLITE_CONFIG_SQLLOG 21 / xSqllog, void* / #define SQLITE_CONFIG_MMAP_SIZE 22 / sqlite3_int64, sqlite3_int64 / #define SQLITE_CONFIG_WIN32_HEAPSIZE 23 / int nByte / #define SQLITE_CONFIG_PCACHE_HDRSZ 24 / int psz / #define SQLITE_CONFIG_PMASZ 25 /* unsigned int szPma / / CAPI3REF: Database Connection Configuration Options These constants are the available integer configuration options that can be passed as the second argument to the [sqlite3_db_config()] interface. New configuration options may be added in future releases of SQLite. Existing configuration options might be discontinued. Applications should check the return code from [sqlite3_db_config()] to make sure that the call worked. ^The [sqlite3_db_config()] interface will return a non-zero [error code] if a discontinued or unsupported configuration option is invoked. <dl> <dt>SQLITE_DBCONFIG_LOOKASIDE</dt> <dd> ^This option takes three additional arguments that determine the [lookaside memory allocator] configuration for the [database connection]. ^The first argument (the third parameter to [sqlite3_db_config()] is a pointer to a memory buffer to use for lookaside memory. ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb may be NULL in which case SQLite will allocate the lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the size of each lookaside buffer slot. ^The third argument is the number of slots. The size of the buffer in the first argument must be greater than or equal to the product of the second and third arguments. The buffer must be aligned to an 8-byte boundary. ^If the second argument to SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally rounded down to the next smaller multiple of 8. ^(The lookaside memory configuration for a database connection can only be changed when that connection is not currently using lookaside memory, or in other words when the "current value" returned by [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero. Any attempt to change the lookaside memory configuration when lookaside memory is in use leaves the configuration unchanged and returns [SQLITE_BUSY].)^</dd> <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt> <dd> ^This option is used to enable or disable the enforcement of [foreign key constraints]. There should be two additional arguments. The first argument is an integer which is 0 to disable FK enforcement, positive to enable FK enforcement or negative to leave FK enforcement unchanged. The second parameter is a pointer to an integer into which is written 0 or 1 to indicate whether FK enforcement is off or on following this call. The second parameter may be a NULL pointer, in which case the FK enforcement setting is not reported back. </dd> <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt> <dd> ^This option is used to enable or disable [CREATE TRIGGER \| triggers]. There should be two additional arguments. The first argument is an integer which is 0 to disable triggers, positive to enable triggers or negative to leave the setting unchanged. The second parameter is a pointer to an integer into which is written 0 or 1 to indicate whether triggers are disabled or enabled following this call. The second parameter may be a NULL pointer, in which case the trigger setting is not reported back. </dd> </dl> / #define SQLITE_DBCONFIG_LOOKASIDE 1001 / void* int int / #define SQLITE_DBCONFIG_ENABLE_FKEY 1002 / int int* / #define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 / int int* / / CAPI3REF: Enable Or Disable Extended Result Codes METHOD: sqlite3 ^The sqlite3_extended_result_codes() routine enables or disables the [extended result codes] feature of SQLite. ^The extended result codes are disabled by default for historical compatibility. / SQLITE_API int SQLITE_STDCALL sqlite3_extended_result_codes(sqlite3, int onoff); /* CAPI3REF: Last Insert Rowid METHOD: sqlite3 ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables) has a unique 64-bit signed integer key called the [ROWID \| "rowid"]. ^The rowid is always available as an undeclared column named ROWID, OID, or _ROWID_ as long as those names are not also used by explicitly declared columns. ^If the table has a column of type [INTEGER PRIMARY KEY] then that column is another alias for the rowid. ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the most recent successful [INSERT] into a rowid table or [virtual table] on database connection D. ^Inserts into [WITHOUT ROWID] tables are not recorded. ^If no successful [INSERT]s into rowid tables have ever occurred on the database connection D, then sqlite3_last_insert_rowid(D) returns zero. ^(If an [INSERT] occurs within a trigger or within a [virtual table] method, then this routine will return the [rowid] of the inserted row as long as the trigger or virtual table method is running. But once the trigger or virtual table method ends, the value returned by this routine reverts to what it was before the trigger or virtual table method began.)^ ^An [INSERT] that fails due to a constraint violation is not a successful [INSERT] and does not change the value returned by this routine. ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK, and INSERT OR ABORT make no changes to the return value of this routine when their insertion fails. ^(When INSERT OR REPLACE encounters a constraint violation, it does not fail. The INSERT continues to completion after deleting rows that caused the constraint problem so INSERT OR REPLACE will always change the return value of this interface.)^ ^For the purposes of this routine, an [INSERT] is considered to be successful even if it is subsequently rolled back. This function is accessible to SQL statements via the [last_insert_rowid() SQL function]. If a separate thread performs a new [INSERT] on the same database connection while the [sqlite3_last_insert_rowid()] function is running and thus changes the last insert [rowid], then the value returned by [sqlite3_last_insert_rowid()] is unpredictable and might not equal either the old or the new last insert [rowid]. / SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_last_insert_rowid(sqlite3); /* CAPI3REF: Count The Number Of Rows Modified METHOD: sqlite3 ^This function returns the number of rows modified, inserted or deleted by the most recently completed INSERT, UPDATE or DELETE statement on the database connection specified by the only parameter. ^Executing any other type of SQL statement does not modify the value returned by this function. ^Only changes made directly by the INSERT, UPDATE or DELETE statement are considered - auxiliary changes caused by [CREATE TRIGGER \| triggers], [foreign key actions] or [REPLACE] constraint resolution are not counted. Changes to a view that are intercepted by [INSTEAD OF trigger \| INSTEAD OF triggers] are not counted. ^The value returned by sqlite3_changes() immediately after an INSERT, UPDATE or DELETE statement run on a view is always zero. Only changes made to real tables are counted. Things are more complicated if the sqlite3_changes() function is executed while a trigger program is running. This may happen if the program uses the [changes() SQL function], or if some other callback function invokes sqlite3_changes() directly. Essentially: <ul> <li> ^(Before entering a trigger program the value returned by sqlite3_changes() function is saved. After the trigger program has finished, the original value is restored.)^ <li> ^(Within a trigger program each INSERT, UPDATE and DELETE statement sets the value returned by sqlite3_changes() upon completion as normal. Of course, this value will not include any changes performed by sub-triggers, as the sqlite3_changes() value will be saved and restored after each sub-trigger has run.)^ </ul> ^This means that if the changes() SQL function (or similar) is used by the first INSERT, UPDATE or DELETE statement within a trigger, it returns the value as set when the calling statement began executing. ^If it is used by the second or subsequent such statement within a trigger program, the value returned reflects the number of rows modified by the previous INSERT, UPDATE or DELETE statement within the same trigger. See also the [sqlite3_total_changes()] interface, the [count_changes pragma], and the [changes() SQL function]. If a separate thread makes changes on the same database connection while [sqlite3_changes()] is running then the value returned ** is unpredictable and not meaningful. / SQLITE_API int SQLITE_STDCALL sqlite3_changes(sqlite3); /* CAPI3REF: Total Number Of Rows Modified METHOD: sqlite3 ^This function returns the total number of rows inserted, modified or deleted by all [INSERT], [UPDATE] or [DELETE] statements completed since the database connection was opened, including those executed as part of trigger programs. ^Executing any other type of SQL statement does not affect the value returned by sqlite3_total_changes(). ^Changes made as part of [foreign key actions] are included in the count, but those made as part of REPLACE constraint resolution are not. ^Changes to a view that are intercepted by INSTEAD OF triggers are not counted. See also the [sqlite3_changes()] interface, the [count_changes pragma], and the [total_changes() SQL function]. If a separate thread makes changes on the same database connection while [sqlite3_total_changes()] is running then the value returned is unpredictable and not meaningful. / SQLITE_API int SQLITE_STDCALL sqlite3_total_changes(sqlite3); /* CAPI3REF: Interrupt A Long-Running Query METHOD: sqlite3 ^This function causes any pending database operation to abort and return at its earliest opportunity. This routine is typically called in response to a user action such as pressing "Cancel" or Ctrl-C where the user wants a long query operation to halt immediately. ^It is safe to call this routine from a thread different from the thread that is currently running the database operation. But it is not safe to call this routine with a [database connection] that is closed or might close before sqlite3_interrupt() returns. ^If an SQL operation is very nearly finished at the time when sqlite3_interrupt() is called, then it might not have an opportunity to be interrupted and might continue to completion. ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT]. ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE that is inside an explicit transaction, then the entire transaction will be rolled back automatically. ^The sqlite3_interrupt(D) call is in effect until all currently running SQL statements on [database connection] D complete. ^Any new SQL statements that are started after the sqlite3_interrupt() call and before the running statements reaches zero are interrupted as if they had been running prior to the sqlite3_interrupt() call. ^New SQL statements that are started after the running statement count reaches zero are not effected by the sqlite3_interrupt(). ^A call to sqlite3_interrupt(D) that occurs when there are no running SQL statements is a no-op and has no effect on SQL statements that are started after the sqlite3_interrupt() call returns. If the database connection closes while [sqlite3_interrupt()] is running then bad things will likely happen. / SQLITE_API void SQLITE_STDCALL sqlite3_interrupt(sqlite3); /* CAPI3REF: Determine If An SQL Statement Is Complete These routines are useful during command-line input to determine if the currently entered text seems to form a complete SQL statement or if additional input is needed before sending the text into SQLite for parsing. ^These routines return 1 if the input string appears to be a complete SQL statement. ^A statement is judged to be complete if it ends with a semicolon token and is not a prefix of a well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within string literals or quoted identifier names or comments are not independent tokens (they are part of the token in which they are embedded) and thus do not count as a statement terminator. ^Whitespace and comments that follow the final semicolon are ignored. ^These routines return 0 if the statement is incomplete. ^If a memory allocation fails, then SQLITE_NOMEM is returned. ^These routines do not parse the SQL statements thus will not detect syntactically incorrect SQL. ^(If SQLite has not been initialized using [sqlite3_initialize()] prior to invoking sqlite3_complete16() then sqlite3_initialize() is invoked automatically by sqlite3_complete16(). If that initialization fails, then the return value from sqlite3_complete16() will be non-zero regardless of whether or not the input SQL is complete.)^ The input to [sqlite3_complete()] must be a zero-terminated UTF-8 string. The input to [sqlite3_complete16()] must be a zero-terminated ** UTF-16 string in native byte order. / SQLITE_API int SQLITE_STDCALL sqlite3_complete(const char sql); SQLITE_API int SQLITE_STDCALL sqlite3_complete16(const void sql); / CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors KEYWORDS: {busy-handler callback} {busy handler} METHOD: sqlite3 ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X that might be invoked with argument P whenever an attempt is made to access a database table associated with [database connection] D when another thread or process has the table locked. The sqlite3_busy_handler() interface is used to implement [sqlite3_busy_timeout()] and [PRAGMA busy_timeout]. ^If the busy callback is NULL, then [SQLITE_BUSY] is returned immediately upon encountering the lock. ^If the busy callback is not NULL, then the callback might be invoked with two arguments. ** ^The first argument to the busy handler is a copy of the void* pointer which is the third argument to sqlite3_busy_handler(). ^The second argument to the busy handler callback is the number of times that the busy handler has been invoked previously for the same locking event. ^If the busy callback returns 0, then no additional attempts are made to access the database and [SQLITE_BUSY] is returned to the application. ^If the callback returns non-zero, then another attempt is made to access the database and the cycle repeats. The presence of a busy handler does not guarantee that it will be invoked when there is lock contention. ^If SQLite determines that invoking the busy handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY] to the application instead of invoking the busy handler. Consider a scenario where one process is holding a read lock that it is trying to promote to a reserved lock and a second process is holding a reserved lock that it is trying to promote to an exclusive lock. The first process cannot proceed because it is blocked by the second and the second process cannot proceed because it is blocked by the first. If both processes invoke the busy handlers, neither will make any progress. Therefore, SQLite returns [SQLITE_BUSY] for the first process, hoping that this will induce the first process to release its read lock and allow the second process to proceed. ^The default busy callback is NULL. ^(There can only be a single busy handler defined for each [database connection]. Setting a new busy handler clears any previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()] or evaluating [PRAGMA busy_timeout=N] will change the busy handler and thus clear any previously set busy handler. The busy callback should not take any actions which modify the database connection that invoked the busy handler. In other words, the busy handler is not reentrant. Any such actions result in undefined behavior. A busy handler must not close the database connection or [prepared statement] that invoked the busy handler. / SQLITE_API int SQLITE_STDCALL sqlite3_busy_handler(sqlite3, int()(void,int), void); / CAPI3REF: Set A Busy Timeout METHOD: sqlite3 ^This routine sets a [sqlite3_busy_handler \| busy handler] that sleeps for a specified amount of time when a table is locked. ^The handler will sleep multiple times until at least "ms" milliseconds of sleeping have accumulated. ^After at least "ms" milliseconds of sleeping, the handler returns 0 which causes [sqlite3_step()] to return [SQLITE_BUSY]. ^Calling this routine with an argument less than or equal to zero turns off all busy handlers. ^(There can only be a single busy handler for a particular [database connection] at any given moment. If another busy handler was defined (using [sqlite3_busy_handler()]) prior to calling this routine, that other busy handler is cleared.)^ ** See also: [PRAGMA busy_timeout] / SQLITE_API int SQLITE_STDCALL sqlite3_busy_timeout(sqlite3, int ms); /* CAPI3REF: Convenience Routines For Running Queries METHOD: sqlite3 This is a legacy interface that is preserved for backwards compatibility. Use of this interface is not recommended. Definition: A <b>result table</b> is memory data structure created by the [sqlite3_get_table()] interface. A result table records the complete query results from one or more queries. The table conceptually has a number of rows and columns. But these numbers are not part of the result table itself. These numbers are obtained separately. Let N be the number of rows and M be the number of columns. A result table is an array of pointers to zero-terminated UTF-8 strings. ** There are (N+1)M elements in the array. The first M pointers point * to zero-terminated strings that contain the names of the columns. The remaining entries all point to query results. NULL values result in NULL pointers. All other values are in their UTF-8 zero-terminated string representation as returned by [sqlite3_column_text()]. A result table might consist of one or more memory allocations. It is not safe to pass a result table directly to [sqlite3_free()]. A result table should be deallocated using [sqlite3_free_table()]. ^(As an example of the result table format, suppose a query result is as follows: <blockquote><pre> Name \| Age ----------------------- Alice \| 43 Bob \| 28 Cindy \| 21 </pre></blockquote> There are two column (M==2) and three rows (N==3). Thus the result table has 8 entries. Suppose the result table is stored in an array names azResult. Then azResult holds this content: <blockquote><pre> azResult[0] = "Name"; azResult[1] = "Age"; azResult[2] = "Alice"; azResult[3] = "43"; azResult[4] = "Bob"; azResult[5] = "28"; azResult[6] = "Cindy"; azResult[7] = "21"; </pre></blockquote>)^ ^The sqlite3_get_table() function evaluates one or more semicolon-separated SQL statements in the zero-terminated UTF-8 string of its 2nd parameter and returns a result table to the pointer given in its 3rd parameter. After the application has finished with the result from sqlite3_get_table(), it must pass the result table pointer to sqlite3_free_table() in order to release the memory that was malloced. Because of the way the [sqlite3_malloc()] happens within sqlite3_get_table(), the calling function must not try to call [sqlite3_free()] directly. Only [sqlite3_free_table()] is able to release the memory properly and safely. The sqlite3_get_table() interface is implemented as a wrapper around [sqlite3_exec()]. The sqlite3_get_table() routine does not have access to any internal data structures of SQLite. It uses only the public interface defined here. As a consequence, errors that occur in the wrapper layer outside of the internal [sqlite3_exec()] call are not reflected in subsequent calls to [sqlite3_errcode()] or ** [sqlite3_errmsg()]. / SQLITE_API int SQLITE_STDCALL sqlite3_get_table( sqlite3 db, /* An open database / const char zSql, /* SQL to be evaluated / char *pazResult, / Results of the query / int pnRow, /* Number of result rows written here / int pnColumn, /* Number of result columns written here / char pzErrmsg / Error msg written here / ); SQLITE_API void SQLITE_STDCALL sqlite3_free_table(char result); / CAPI3REF: Formatted String Printing Functions These routines are work-alikes of the "printf()" family of functions from the standard C library. These routines understand most of the common K&R formatting options, plus some additional non-standard formats, detailed below. Note that some of the more obscure formatting options from recent C-library standards are omitted from this implementation. ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their results into memory obtained from [sqlite3_malloc()]. The strings returned by these two routines should be released by [sqlite3_free()]. ^Both routines return a NULL pointer if [sqlite3_malloc()] is unable to allocate enough memory to hold the resulting string. ^(The sqlite3_snprintf() routine is similar to "snprintf()" from the standard C library. The result is written into the buffer supplied as the second parameter whose size is given by the first parameter. Note that the order of the first two parameters is reversed from snprintf().)^ This is an historical accident that cannot be fixed without breaking backwards compatibility. ^(Note also that sqlite3_snprintf() returns a pointer to its buffer instead of the number of characters actually written into the buffer.)^ We admit that the number of characters written would be a more useful return value but we cannot change the implementation of sqlite3_snprintf() now without breaking compatibility. ^As long as the buffer size is greater than zero, sqlite3_snprintf() guarantees that the buffer is always zero-terminated. ^The first parameter "n" is the total size of the buffer, including space for the zero terminator. So the longest string that can be completely written will be n-1 characters. ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf(). These routines all implement some additional formatting options that are useful for constructing SQL statements. All of the usual printf() formatting options apply. In addition, there is are "%q", "%Q", "%w" and "%z" options. ^(The %q option works like %s in that it substitutes a nul-terminated string from the argument list. But %q also doubles every '\'' character. %q is designed for use inside a string literal.)^ By doubling each '\'' character it escapes that character and allows it to be inserted into the string. For example, assume the string variable zText contains text as follows: <blockquote><pre> char zText = "It's a happy day!"; * </pre></blockquote> One can use this text in an SQL statement as follows: <blockquote><pre> ** char zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText); * sqlite3_exec(db, zSQL, 0, 0, 0); sqlite3_free(zSQL); </pre></blockquote> Because the %q format string is used, the '\'' character in zText is escaped and the SQL generated is as follows: <blockquote><pre> INSERT INTO table1 VALUES('It''s a happy day!') </pre></blockquote> This is correct. Had we used %s instead of %q, the generated SQL would have looked like this: <blockquote><pre> INSERT INTO table1 VALUES('It's a happy day!'); </pre></blockquote> This second example is an SQL syntax error. As a general rule you should always use %q instead of %s when inserting text into a string literal. ^(The %Q option works like %q except it also adds single quotes around the outside of the total string. Additionally, if the parameter in the argument list is a NULL pointer, %Q substitutes the text "NULL" (without single quotes).)^ So, for example, one could say: <blockquote><pre> ** char zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText); * sqlite3_exec(db, zSQL, 0, 0, 0); sqlite3_free(zSQL); </pre></blockquote> The code above will render a correct SQL statement in the zSQL variable even if the zText variable is a NULL pointer. ^(The "%w" formatting option is like "%q" except that it expects to be contained within double-quotes instead of single quotes, and it escapes the double-quote character instead of the single-quote character.)^ The "%w" formatting option is intended for safely inserting table and column names into a constructed SQL statement. ^(The "%z" formatting option works like "%s" but with the addition that after the string has been read and copied into ** the result, [sqlite3_free()] is called on the input string.)^ / SQLITE_API char SQLITE_CDECL sqlite3_mprintf(const char,...); SQLITE_API char SQLITE_STDCALL sqlite3_vmprintf(const char, va_list); SQLITE_API char SQLITE_CDECL sqlite3_snprintf(int,char,const char, ...); SQLITE_API char SQLITE_STDCALL sqlite3_vsnprintf(int,char,const char, va_list); / CAPI3REF: Memory Allocation Subsystem The SQLite core uses these three routines for all of its own internal memory allocation needs. "Core" in the previous sentence does not include operating-system specific VFS implementation. The Windows VFS uses native malloc() and free() for some operations. ^The sqlite3_malloc() routine returns a pointer to a block of memory at least N bytes in length, where N is the parameter. ^If sqlite3_malloc() is unable to obtain sufficient free memory, it returns a NULL pointer. ^If the parameter N to sqlite3_malloc() is zero or negative then sqlite3_malloc() returns a NULL pointer. ^The sqlite3_malloc64(N) routine works just like sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead of a signed 32-bit integer. ^Calling sqlite3_free() with a pointer previously returned by sqlite3_malloc() or sqlite3_realloc() releases that memory so that it might be reused. ^The sqlite3_free() routine is a no-op if is called with a NULL pointer. Passing a NULL pointer to sqlite3_free() is harmless. After being freed, memory should neither be read nor written. Even reading previously freed memory might result in a segmentation fault or other severe error. Memory corruption, a segmentation fault, or other severe error might result if sqlite3_free() is called with a non-NULL pointer that was not obtained from sqlite3_malloc() or sqlite3_realloc(). ^The sqlite3_realloc(X,N) interface attempts to resize a prior memory allocation X to be at least N bytes. ^If the X parameter to sqlite3_realloc(X,N) is a NULL pointer then its behavior is identical to calling sqlite3_malloc(N). ^If the N parameter to sqlite3_realloc(X,N) is zero or negative then the behavior is exactly the same as calling sqlite3_free(X). ^sqlite3_realloc(X,N) returns a pointer to a memory allocation of at least N bytes in size or NULL if insufficient memory is available. ^If M is the size of the prior allocation, then min(N,M) bytes of the prior allocation are copied into the beginning of buffer returned by sqlite3_realloc(X,N) and the prior allocation is freed. ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the prior allocation is not freed. ^The sqlite3_realloc64(X,N) interfaces works the same as sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead of a 32-bit signed integer. ^If X is a memory allocation previously obtained from sqlite3_malloc(), sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then sqlite3_msize(X) returns the size of that memory allocation in bytes. ^The value returned by sqlite3_msize(X) might be larger than the number of bytes requested when X was allocated. ^If X is a NULL pointer then sqlite3_msize(X) returns zero. If X points to something that is not the beginning of memory allocation, or if it points to a formerly valid memory allocation that has now been freed, then the behavior of sqlite3_msize(X) is undefined and possibly harmful. ^The memory returned by sqlite3_malloc(), sqlite3_realloc(), sqlite3_malloc64(), and sqlite3_realloc64() is always aligned to at least an 8 byte boundary, or to a 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time option is used. In SQLite version 3.5.0 and 3.5.1, it was possible to define the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in implementation of these routines to be omitted. That capability is no longer provided. Only built-in memory allocators can be used. Prior to SQLite version 3.7.10, the Windows OS interface layer called the system malloc() and free() directly when converting filenames between the UTF-8 encoding used by SQLite and whatever filename encoding is used by the particular Windows installation. Memory allocation errors were detected, but they were reported back as [SQLITE_CANTOPEN] or [SQLITE_IOERR] rather than [SQLITE_NOMEM]. The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()] must be either NULL or else pointers obtained from a prior invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have not yet been released. The application must not read or write any part of a block of memory after it has been released using [sqlite3_free()] or [sqlite3_realloc()]. / SQLITE_API void SQLITE_STDCALL sqlite3_malloc(int); SQLITE_API void SQLITE_STDCALL sqlite3_malloc64(sqlite3_uint64); SQLITE_API void SQLITE_STDCALL sqlite3_realloc(void, int); SQLITE_API void SQLITE_STDCALL sqlite3_realloc64(void, sqlite3_uint64); SQLITE_API void SQLITE_STDCALL sqlite3_free(void); SQLITE_API sqlite3_uint64 SQLITE_STDCALL sqlite3_msize(void); / CAPI3REF: Memory Allocator Statistics SQLite provides these two interfaces for reporting on the status of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()] routines, which form the built-in memory allocation subsystem. ^The [sqlite3_memory_used()] routine returns the number of bytes of memory currently outstanding (malloced but not freed). ^The [sqlite3_memory_highwater()] routine returns the maximum value of [sqlite3_memory_used()] since the high-water mark was last reset. ^The values returned by [sqlite3_memory_used()] and [sqlite3_memory_highwater()] include any overhead added by SQLite in its implementation of [sqlite3_malloc()], but not overhead added by the any underlying system library routines that [sqlite3_malloc()] may call. ^The memory high-water mark is reset to the current value of [sqlite3_memory_used()] if and only if the parameter to [sqlite3_memory_highwater()] is true. ^The value returned by [sqlite3_memory_highwater(1)] is the high-water mark ** prior to the reset. / SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_memory_used(void); SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_memory_highwater(int resetFlag); / CAPI3REF: Pseudo-Random Number Generator SQLite contains a high-quality pseudo-random number generator (PRNG) used to select random [ROWID \| ROWIDs] when inserting new records into a table that already uses the largest possible [ROWID]. The PRNG is also used for the build-in random() and randomblob() SQL functions. This interface allows applications to access the same PRNG for other purposes. ^A call to this routine stores N bytes of randomness into buffer P. ^The P parameter can be a NULL pointer. ^If this routine has not been previously called or if the previous call had N less than one or a NULL pointer for P, then the PRNG is seeded using randomness obtained from the xRandomness method of the default [sqlite3_vfs] object. ^If the previous call to this routine had an N of 1 or more and a non-NULL P then the pseudo-randomness is generated internally and without recourse to the [sqlite3_vfs] xRandomness ** method. / SQLITE_API void SQLITE_STDCALL sqlite3_randomness(int N, void P); /* CAPI3REF: Compile-Time Authorization Callbacks METHOD: sqlite3 ^This routine registers an authorizer callback with a particular [database connection], supplied in the first argument. ^The authorizer callback is invoked as SQL statements are being compiled by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()], [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various points during the compilation process, as logic is being created to perform various actions, the authorizer callback is invoked to see if those actions are allowed. ^The authorizer callback should return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the specific action but allow the SQL statement to continue to be compiled, or [SQLITE_DENY] to cause the entire SQL statement to be rejected with an error. ^If the authorizer callback returns any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY] then the [sqlite3_prepare_v2()] or equivalent call that triggered the authorizer will fail with an error message. When the callback returns [SQLITE_OK], that means the operation requested is ok. ^When the callback returns [SQLITE_DENY], the [sqlite3_prepare_v2()] or equivalent call that triggered the authorizer will fail with an error message explaining that access is denied. ^The first parameter to the authorizer callback is a copy of the third parameter to the sqlite3_set_authorizer() interface. ^The second parameter to the callback is an integer [SQLITE_COPY \| action code] that specifies the particular action to be authorized. ^The third through sixth parameters to the callback are zero-terminated strings that contain additional details about the action to be authorized. ^If the action code is [SQLITE_READ] and the callback returns [SQLITE_IGNORE] then the [prepared statement] statement is constructed to substitute a NULL value in place of the table column that would have been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE] return can be used to deny an untrusted user access to individual columns of a table. ^If the action code is [SQLITE_DELETE] and the callback returns [SQLITE_IGNORE] then the [DELETE] operation proceeds but the [truncate optimization] is disabled and all rows are deleted individually. An authorizer is used when [sqlite3_prepare \| preparing] SQL statements from an untrusted source, to ensure that the SQL statements do not try to access data they are not allowed to see, or that they do not try to execute malicious statements that damage the database. For example, an application may allow a user to enter arbitrary SQL queries for evaluation by a database. But the application does not want the user to be able to make arbitrary changes to the database. An authorizer could then be put in place while the user-entered SQL is being [sqlite3_prepare \| prepared] that disallows everything except [SELECT] statements. Applications that need to process SQL from untrusted sources might also consider lowering resource limits using [sqlite3_limit()] and limiting database size using the [max_page_count] [PRAGMA] in addition to using an authorizer. ^(Only a single authorizer can be in place on a database connection at a time. Each call to sqlite3_set_authorizer overrides the previous call.)^ ^Disable the authorizer by installing a NULL callback. The authorizer is disabled by default. The authorizer callback must not do anything that will modify the database connection that invoked the authorizer callback. Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their database connections for the meaning of "modify" in this paragraph. ^When [sqlite3_prepare_v2()] is used to prepare a statement, the statement might be re-prepared during [sqlite3_step()] due to a schema change. Hence, the application should ensure that the correct authorizer callback remains in place during the [sqlite3_step()]. ^Note that the authorizer callback is invoked only during [sqlite3_prepare()] or its variants. Authorization is not performed during statement evaluation in [sqlite3_step()], unless as stated in the previous paragraph, sqlite3_step() invokes ** sqlite3_prepare_v2() to reprepare a statement after a schema change. / SQLITE_API int SQLITE_STDCALL sqlite3_set_authorizer( sqlite3, int (xAuth)(void,int,const char,const char,const char,const char), void pUserData ); / CAPI3REF: Authorizer Return Codes The [sqlite3_set_authorizer \| authorizer callback function] must return either [SQLITE_OK] or one of these two constants in order to signal SQLite whether or not the action is permitted. See the [sqlite3_set_authorizer \| authorizer documentation] for additional information. Note that SQLITE_IGNORE is also used as a [conflict resolution mode] returned from the [sqlite3_vtab_on_conflict()] interface. / #define SQLITE_DENY 1 / Abort the SQL statement with an error / #define SQLITE_IGNORE 2 / Don't allow access, but don't generate an error / / CAPI3REF: Authorizer Action Codes The [sqlite3_set_authorizer()] interface registers a callback function that is invoked to authorize certain SQL statement actions. The second parameter to the callback is an integer code that specifies what action is being authorized. These are the integer action codes that the authorizer callback may be passed. These action code values signify what kind of operation is to be authorized. The 3rd and 4th parameters to the authorization callback function will be parameters or NULL depending on which of these codes is used as the second parameter. ^(The 5th parameter to the authorizer callback is the name of the database ("main", "temp", etc.) if applicable.)^ ^The 6th parameter to the authorizer callback is the name of the inner-most trigger or view that is responsible for the access attempt or NULL if this access attempt is directly from ** top-level SQL code. / /**************************************** 3rd ******** 4th ********/ #define SQLITE_CREATE_INDEX 1 / Index Name Table Name / #define SQLITE_CREATE_TABLE 2 / Table Name NULL / #define SQLITE_CREATE_TEMP_INDEX 3 / Index Name Table Name / #define SQLITE_CREATE_TEMP_TABLE 4 / Table Name NULL / #define SQLITE_CREATE_TEMP_TRIGGER 5 / Trigger Name Table Name / #define SQLITE_CREATE_TEMP_VIEW 6 / View Name NULL / #define SQLITE_CREATE_TRIGGER 7 / Trigger Name Table Name / #define SQLITE_CREATE_VIEW 8 / View Name NULL / #define SQLITE_DELETE 9 / Table Name NULL / #define SQLITE_DROP_INDEX 10 / Index Name Table Name / #define SQLITE_DROP_TABLE 11 / Table Name NULL / #define SQLITE_DROP_TEMP_INDEX 12 / Index Name Table Name / #define SQLITE_DROP_TEMP_TABLE 13 / Table Name NULL / #define SQLITE_DROP_TEMP_TRIGGER 14 / Trigger Name Table Name / #define SQLITE_DROP_TEMP_VIEW 15 / View Name NULL / #define SQLITE_DROP_TRIGGER 16 / Trigger Name Table Name / #define SQLITE_DROP_VIEW 17 / View Name NULL / #define SQLITE_INSERT 18 / Table Name NULL / #define SQLITE_PRAGMA 19 / Pragma Name 1st arg or NULL / #define SQLITE_READ 20 / Table Name Column Name / #define SQLITE_SELECT 21 / NULL NULL / #define SQLITE_TRANSACTION 22 / Operation NULL / #define SQLITE_UPDATE 23 / Table Name Column Name / #define SQLITE_ATTACH 24 / Filename NULL / #define SQLITE_DETACH 25 / Database Name NULL / #define SQLITE_ALTER_TABLE 26 / Database Name Table Name / #define SQLITE_REINDEX 27 / Index Name NULL / #define SQLITE_ANALYZE 28 / Table Name NULL / #define SQLITE_CREATE_VTABLE 29 / Table Name Module Name / #define SQLITE_DROP_VTABLE 30 / Table Name Module Name / #define SQLITE_FUNCTION 31 / NULL Function Name / #define SQLITE_SAVEPOINT 32 / Operation Savepoint Name / #define SQLITE_COPY 0 / No longer used / #define SQLITE_RECURSIVE 33 / NULL NULL / / CAPI3REF: Tracing And Profiling Functions METHOD: sqlite3 These routines register callback functions that can be used for tracing and profiling the execution of SQL statements. ^The callback function registered by sqlite3_trace() is invoked at various times when an SQL statement is being run by [sqlite3_step()]. ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the SQL statement text as the statement first begins executing. ^(Additional sqlite3_trace() callbacks might occur as each triggered subprogram is entered. The callbacks for triggers contain a UTF-8 SQL comment that identifies the trigger.)^ The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit the length of [bound parameter] expansion in the output of sqlite3_trace(). ^The callback function registered by sqlite3_profile() is invoked as each SQL statement finishes. ^The profile callback contains the original statement text and an estimate of wall-clock time of how long that statement took to run. ^The profile callback time is in units of nanoseconds, however the current implementation is only capable of millisecond resolution so the six least significant digits in the time are meaningless. Future versions of SQLite might provide greater resolution on the profiler callback. The sqlite3_profile() function is considered experimental and is ** subject to change in future versions of SQLite. / SQLITE_API void SQLITE_STDCALL sqlite3_trace(sqlite3, void(xTrace)(void,const char), void); SQLITE_API SQLITE_EXPERIMENTAL void SQLITE_STDCALL sqlite3_profile(sqlite3, void(xProfile)(void,const char,sqlite3_uint64), void); / CAPI3REF: Query Progress Callbacks METHOD: sqlite3 ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback function X to be invoked periodically during long running calls to [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for database connection D. An example use for this interface is to keep a GUI updated during a large query. ^The parameter P is passed through as the only parameter to the callback function X. ^The parameter N is the approximate number of [virtual machine instructions] that are evaluated between successive invocations of the callback X. ^If N is less than one then the progress handler is disabled. ^Only a single progress handler may be defined at one time per [database connection]; setting a new progress handler cancels the old one. ^Setting parameter X to NULL disables the progress handler. ^The progress handler is also disabled by setting N to a value less than 1. ^If the progress callback returns non-zero, the operation is interrupted. This feature can be used to implement a "Cancel" button on a GUI progress dialog box. The progress handler callback must not do anything that will modify the database connection that invoked the progress handler. Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their database connections for the meaning of "modify" in this paragraph. / SQLITE_API void SQLITE_STDCALL sqlite3_progress_handler(sqlite3, int, int()(void), void); / CAPI3REF: Opening A New Database Connection CONSTRUCTOR: sqlite3 ^These routines open an SQLite database file as specified by the filename argument. ^The filename argument is interpreted as UTF-8 for sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte order for sqlite3_open16(). ^(A [database connection] handle is usually returned in ppDb, even if an error occurs. The only exception is that * if SQLite is unable to allocate memory to hold the [sqlite3] object, ** a NULL will be written into ppDb instead of a pointer to the [sqlite3] * object.)^ ^(If the database is opened (and/or created) successfully, then [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain an English language description of the error following a failure of any of the sqlite3_open() routines. ^The default encoding will be UTF-8 for databases created using sqlite3_open() or sqlite3_open_v2(). ^The default encoding for databases created using sqlite3_open16() will be UTF-16 in the native byte order. Whether or not an error occurs when it is opened, resources associated with the [database connection] handle should be released by passing it to [sqlite3_close()] when it is no longer required. The sqlite3_open_v2() interface works like sqlite3_open() except that it accepts two additional parameters for additional control over the new database connection. ^(The flags parameter to sqlite3_open_v2() can take one of the following three values, optionally combined with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE], [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^ <dl> ^(<dt>[SQLITE_OPEN_READONLY]</dt> <dd>The database is opened in read-only mode. If the database does not already exist, an error is returned.</dd>)^ ^(<dt>[SQLITE_OPEN_READWRITE]</dt> <dd>The database is opened for reading and writing if possible, or reading only if the file is write protected by the operating system. In either case the database must already exist, otherwise an error is returned.</dd>)^ ^(<dt>[SQLITE_OPEN_READWRITE] \| [SQLITE_OPEN_CREATE]</dt> <dd>The database is opened for reading and writing, and is created if it does not already exist. This is the behavior that is always used for sqlite3_open() and sqlite3_open16().</dd>)^ </dl> If the 3rd parameter to sqlite3_open_v2() is not one of the combinations shown above optionally combined with other [SQLITE_OPEN_READONLY \| SQLITE_OPEN_* bits] then the behavior is undefined. ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection opens in the multi-thread [threading mode] as long as the single-thread mode has not been set at compile-time or start-time. ^If the [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens in the serialized [threading mode] unless single-thread was previously selected at compile-time or start-time. ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be eligible to use [shared cache mode], regardless of whether or not shared cache is enabled using [sqlite3_enable_shared_cache()]. ^The [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not participate in [shared cache mode] even if it is enabled. ^The fourth parameter to sqlite3_open_v2() is the name of the [sqlite3_vfs] object that defines the operating system interface that the new database connection should use. ^If the fourth parameter is a NULL pointer then the default [sqlite3_vfs] object is used. ^If the filename is ":memory:", then a private, temporary in-memory database is created for the connection. ^This in-memory database will vanish when the database connection is closed. Future versions of SQLite might make use of additional special filenames that begin with the ":" character. It is recommended that when a database filename actually does begin with a ":" character you should prefix the filename with a pathname such as "./" to avoid ambiguity. ^If the filename is an empty string, then a private, temporary on-disk database will be created. ^This private database will be automatically deleted as soon as the database connection is closed. [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3> ^If [URI filename] interpretation is enabled, and the filename argument begins with "file:", then the filename is interpreted as a URI. ^URI filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is set in the fourth argument to sqlite3_open_v2(), or if it has been enabled globally using the [SQLITE_CONFIG_URI] option with the [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option. As of SQLite version 3.7.7, URI filename interpretation is turned off by default, but future releases of SQLite might enable URI filename interpretation by default. See "[URI filenames]" for additional information. URI filenames are parsed according to RFC 3986. ^If the URI contains an authority, then it must be either an empty string or the string "localhost". ^If the authority is not an empty string or "localhost", an error is returned to the caller. ^The fragment component of a URI, if present, is ignored. ^SQLite uses the path component of the URI as the name of the disk file which contains the database. ^If the path begins with a '/' character, then it is interpreted as an absolute path. ^If the path does not begin with a '/' (meaning that the authority section is omitted from the URI) then the path is interpreted as a relative path. ^(On windows, the first component of an absolute path is a drive specification (e.g. "C:").)^ [[core URI query parameters]] The query component of a URI may contain parameters that are interpreted either by SQLite itself, or by a [VFS \| custom VFS implementation]. SQLite and its built-in [VFSes] interpret the following query parameters: <ul> <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of a VFS object that provides the operating system interface that should be used to access the database file on disk. ^If this option is set to an empty string the default VFS object is used. ^Specifying an unknown VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is present, then the VFS specified by the option takes precedence over the value passed as the fourth parameter to sqlite3_open_v2(). <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw", "rwc", or "memory". Attempting to set it to any other value is an error)^. ^If "ro" is specified, then the database is opened for read-only access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the third argument to sqlite3_open_v2(). ^If the mode option is set to "rw", then the database is opened for read-write (but not create) access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had been set. ^Value "rwc" is equivalent to setting both SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE. ^If the mode option is set to "memory" then a pure [in-memory database] that never reads or writes from disk is used. ^It is an error to specify a value for the mode parameter that is less restrictive than that specified by the flags passed in the third parameter to sqlite3_open_v2(). <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or "private". ^Setting it to "shared" is equivalent to setting the SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to sqlite3_open_v2(). ^Setting the cache parameter to "private" is equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit. ^If sqlite3_open_v2() is used and the "cache" parameter is present in a URI filename, its value overrides any behavior requested by setting SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag. <li> <b>psow</b>: ^The psow parameter indicates whether or not the [powersafe overwrite] property does or does not apply to the storage media on which the database file resides. <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter which if set disables file locking in rollback journal modes. This is useful for accessing a database on a filesystem that does not support locking. Caution: Database corruption might result if two or more processes write to the same database and any one of those processes uses nolock=1. <li> <b>immutable</b>: ^The immutable parameter is a boolean query parameter that indicates that the database file is stored on read-only media. ^When immutable is set, SQLite assumes that the database file cannot be changed, even by a process with higher privilege, and so the database is opened read-only and all locking and change detection is disabled. Caution: Setting the immutable property on a database file that does in fact change can result in incorrect query results and/or [SQLITE_CORRUPT] errors. See also: [SQLITE_IOCAP_IMMUTABLE]. </ul> ^Specifying an unknown parameter in the query component of a URI is not an error. Future versions of SQLite might understand additional query parameters. See "[query parameters with special meaning to SQLite]" for additional information. [[URI filename examples]] <h3>URI filename examples</h3> <table border="1" align=center cellpadding=5> <tr><th> URI filenames <th> Results <tr><td> file:data.db <td> Open the file "data.db" in the current directory. <tr><td> file:/home/fred/data.db<br> file:///home/fred/data.db <br> file://localhost/home/fred/data.db <br> <td> Open the database file "/home/fred/data.db". <tr><td> file://darkstar/home/fred/data.db <td> An error. "darkstar" is not a recognized authority. <tr><td style="white-space:nowrap"> file:///C:/Documents%20and%20Settings/fred/Desktop/data.db <td> Windows only: Open the file "data.db" on fred's desktop on drive C:. Note that the %20 escaping in this example is not strictly necessary - space characters can be used literally in URI filenames. <tr><td> file:data.db?mode=ro&cache=private <td> Open file "data.db" in the current directory for read-only access. Regardless of whether or not shared-cache mode is enabled by default, use a private cache. <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td> Open file "/home/fred/data.db". Use the special VFS "unix-dotfile" that uses dot-files in place of posix advisory locking. <tr><td> file:data.db?mode=readonly <td> An error. "readonly" is not a valid option for the "mode" parameter. </table> ^URI hexadecimal escape sequences (%HH) are supported within the path and query components of a URI. A hexadecimal escape sequence consists of a percent sign - "%" - followed by exactly two hexadecimal digits specifying an octet value. ^Before the path or query components of a URI filename are interpreted, they are encoded using UTF-8 and all hexadecimal escape sequences replaced by a single byte containing the corresponding octet. If this process generates an invalid UTF-8 encoding, the results are undefined. <b>Note to Windows users:</b> The encoding used for the filename argument of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever codepage is currently defined. Filenames containing international characters must be converted to UTF-8 prior to passing them into sqlite3_open() or sqlite3_open_v2(). <b>Note to Windows Runtime users:</b> The temporary directory must be set prior to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various features that require the use of temporary files may fail. See also: [sqlite3_temp_directory] / SQLITE_API int SQLITE_STDCALL sqlite3_open( const char filename, /* Database filename (UTF-8) / sqlite3 ppDb / OUT: SQLite db handle / ); SQLITE_API int SQLITE_STDCALL sqlite3_open16( const void filename, /* Database filename (UTF-16) / sqlite3 ppDb / OUT: SQLite db handle / ); SQLITE_API int SQLITE_STDCALL sqlite3_open_v2( const char filename, /* Database filename (UTF-8) / sqlite3 ppDb, / OUT: SQLite db handle / int flags, / Flags / const char zVfs /* Name of VFS module to use / ); / CAPI3REF: Obtain Values For URI Parameters These are utility routines, useful to VFS implementations, that check to see if a database file was a URI that contained a specific query parameter, and if so obtains the value of that query parameter. If F is the database filename pointer passed into the xOpen() method of a VFS implementation when the flags parameter to xOpen() has one or more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and P is the name of the query parameter, then sqlite3_uri_parameter(F,P) returns the value of the P parameter if it exists or a NULL pointer if P does not appear as a query parameter on F. If P is a query parameter of F has no explicit value, then sqlite3_uri_parameter(F,P) returns a pointer to an empty string. The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean parameter and returns true (1) or false (0) according to the value of P. The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the value of query parameter P is one of "yes", "true", or "on" in any case or if the value begins with a non-zero number. The sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of query parameter P is one of "no", "false", or "off" in any case or if the value begins with a numeric zero. If P is not a query parameter on F or if the value of P is does not match any of the above, then sqlite3_uri_boolean(F,P,B) returns (B!=0). The sqlite3_uri_int64(F,P,D) routine converts the value of P into a 64-bit signed integer and returns that integer, or D if P does not exist. If the value of P is something other than an integer, then zero is returned. If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and is not a database file pathname pointer that SQLite passed into the xOpen VFS method, then the behavior of this routine is undefined and probably ** undesirable. / SQLITE_API const char SQLITE_STDCALL sqlite3_uri_parameter(const char zFilename, const char zParam); SQLITE_API int SQLITE_STDCALL sqlite3_uri_boolean(const char zFile, const char zParam, int bDefault); SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_uri_int64(const char, const char, sqlite3_int64); /* CAPI3REF: Error Codes And Messages METHOD: sqlite3 ^If the most recent sqlite3_* API call associated with [database connection] D failed, then the sqlite3_errcode(D) interface returns the numeric [result code] or [extended result code] for that API call. If the most recent API call was successful, then the return value from sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode() interface is the same except that it always returns the [extended result code] even when extended result codes are disabled. ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language text that describes the error, as either UTF-8 or UTF-16 respectively. ^(Memory to hold the error message string is managed internally. The application does not need to worry about freeing the result. However, the error string might be overwritten or deallocated by subsequent calls to other SQLite interface functions.)^ ^The sqlite3_errstr() interface returns the English-language text that describes the [result code], as UTF-8. ^(Memory to hold the error message string is managed internally and must not be freed by the application)^. When the serialized [threading mode] is in use, it might be the case that a second error occurs on a separate thread in between the time of the first error and the call to these interfaces. When that happens, the second error will be reported since these interfaces always report the most recent result. To avoid this, each thread can obtain exclusive use of the [database connection] D by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after all calls to the interfaces listed here are completed. If an interface fails with SQLITE_MISUSE, that means the interface was invoked incorrectly by the application. In that case, the ** error code and message may or may not be set. / SQLITE_API int SQLITE_STDCALL sqlite3_errcode(sqlite3 db); SQLITE_API int SQLITE_STDCALL sqlite3_extended_errcode(sqlite3 db); SQLITE_API const char SQLITE_STDCALL sqlite3_errmsg(sqlite3); SQLITE_API const void SQLITE_STDCALL sqlite3_errmsg16(sqlite3); SQLITE_API const char SQLITE_STDCALL sqlite3_errstr(int); /* CAPI3REF: Prepared Statement Object KEYWORDS: {prepared statement} {prepared statements} An instance of this object represents a single SQL statement that has been compiled into binary form and is ready to be evaluated. Think of each SQL statement as a separate computer program. The original SQL text is source code. A prepared statement object is the compiled object code. All SQL must be converted into a prepared statement before it can be run. The life-cycle of a prepared statement object usually goes like this: <ol> <li> Create the prepared statement object using [sqlite3_prepare_v2()]. <li> Bind values to [parameters] using the sqlite3_bind_() * interfaces. <li> Run the SQL by calling [sqlite3_step()] one or more times. <li> Reset the prepared statement using [sqlite3_reset()] then go back to step 2. Do this zero or more times. <li> Destroy the object using [sqlite3_finalize()]. ** </ol> / typedef struct sqlite3_stmt sqlite3_stmt; / CAPI3REF: Run-time Limits METHOD: sqlite3 ^(This interface allows the size of various constructs to be limited on a connection by connection basis. The first parameter is the [database connection] whose limit is to be set or queried. The second parameter is one of the [limit categories] that define a class of constructs to be size limited. The third parameter is the new limit for that construct.)^ ^If the new limit is a negative number, the limit is unchanged. ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a [limits \| hard upper bound] set at compile-time by a C preprocessor macro called [limits \| SQLITE_MAX_<i>NAME</i>]. (The "_LIMIT_" in the name is changed to "_MAX_".))^ ^Attempts to increase a limit above its hard upper bound are silently truncated to the hard upper bound. ^Regardless of whether or not the limit was changed, the [sqlite3_limit()] interface returns the prior value of the limit. ^Hence, to find the current value of a limit without changing it, simply invoke this interface with the third parameter set to -1. Run-time limits are intended for use in applications that manage both their own internal database and also databases that are controlled by untrusted external sources. An example application might be a web browser that has its own databases for storing history and separate databases controlled by JavaScript applications downloaded off the Internet. The internal databases can be given the large, default limits. Databases managed by external sources can be given much smaller limits designed to prevent a denial of service attack. Developers might also want to use the [sqlite3_set_authorizer()] interface to further control untrusted SQL. The size of the database created by an untrusted script can be contained using the [max_page_count] [PRAGMA]. New run-time limit categories may be added in future releases. / SQLITE_API int SQLITE_STDCALL sqlite3_limit(sqlite3, int id, int newVal); /* CAPI3REF: Run-Time Limit Categories KEYWORDS: {limit category} {limit categories} * These constants define various performance limits that can be lowered at run-time using [sqlite3_limit()]. The synopsis of the meanings of the various limits is shown below. Additional information is available at [limits \| Limits in SQLite]. <dl> [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt> <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^ [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt> <dd>The maximum length of an SQL statement, in bytes.</dd>)^ [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt> <dd>The maximum number of columns in a table definition or in the result set of a [SELECT] or the maximum number of columns in an index or in an ORDER BY or GROUP BY clause.</dd>)^ [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt> <dd>The maximum depth of the parse tree on any expression.</dd>)^ [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt> <dd>The maximum number of terms in a compound SELECT statement.</dd>)^ [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt> <dd>The maximum number of instructions in a virtual machine program used to implement an SQL statement. This limit is not currently enforced, though that might be added in some future release of SQLite.</dd>)^ [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt> <dd>The maximum number of arguments on a function.</dd>)^ [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt> <dd>The maximum number of [ATTACH \| attached databases].)^</dd> [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]] ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt> <dd>The maximum length of the pattern argument to the [LIKE] or [GLOB] operators.</dd>)^ [[SQLITE_LIMIT_VARIABLE_NUMBER]] ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt> <dd>The maximum index number of any [parameter] in an SQL statement.)^ [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt> <dd>The maximum depth of recursion for triggers.</dd>)^ [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt> <dd>The maximum number of auxiliary worker threads that a single [prepared statement] may start.</dd>)^ ** </dl> / #define SQLITE_LIMIT_LENGTH 0 #define SQLITE_LIMIT_SQL_LENGTH 1 #define SQLITE_LIMIT_COLUMN 2 #define SQLITE_LIMIT_EXPR_DEPTH 3 #define SQLITE_LIMIT_COMPOUND_SELECT 4 #define SQLITE_LIMIT_VDBE_OP 5 #define SQLITE_LIMIT_FUNCTION_ARG 6 #define SQLITE_LIMIT_ATTACHED 7 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8 #define SQLITE_LIMIT_VARIABLE_NUMBER 9 #define SQLITE_LIMIT_TRIGGER_DEPTH 10 #define SQLITE_LIMIT_WORKER_THREADS 11 / CAPI3REF: Compiling An SQL Statement KEYWORDS: {SQL statement compiler} METHOD: sqlite3 CONSTRUCTOR: sqlite3_stmt To execute an SQL query, it must first be compiled into a byte-code program using one of these routines. The first argument, "db", is a [database connection] obtained from a prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or [sqlite3_open16()]. The database connection must not have been closed. The second argument, "zSql", is the statement to be compiled, encoded as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2() interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2() use UTF-16. ^If the nByte argument is negative, then zSql is read up to the first zero terminator. ^If nByte is positive, then it is the number of bytes read from zSql. ^If nByte is zero, then no prepared statement is generated. If the caller knows that the supplied string is nul-terminated, then there is a small performance advantage to passing an nByte parameter that is the number of bytes in the input string <i>including</i> the nul-terminator. ** ^If pzTail is not NULL then pzTail is made to point to the first byte * past the end of the first SQL statement in zSql. These routines only ** compile the first statement in zSql, so pzTail is left pointing to * what remains uncompiled. ^ppStmt is left pointing to a compiled [prepared statement] that can be * executed using [sqlite3_step()]. ^If there is an error, ppStmt is set * to NULL. ^If the input text contains no SQL (if the input is an empty ** string or a comment) then ppStmt is set to NULL. * The calling procedure is responsible for deleting the compiled SQL statement using [sqlite3_finalize()] after it has finished with it. ppStmt may not be NULL. ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK]; otherwise an [error code] is returned. The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are recommended for all new programs. The two older interfaces are retained for backwards compatibility, but their use is discouraged. ^In the "v2" interfaces, the prepared statement that is returned (the [sqlite3_stmt] object) contains a copy of the original SQL text. This causes the [sqlite3_step()] interface to behave differently in three ways: <ol> <li> ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it always used to do, [sqlite3_step()] will automatically recompile the SQL statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY] retries will occur before sqlite3_step() gives up and returns an error. </li> <li> ^When an error occurs, [sqlite3_step()] will return one of the detailed [error codes] or [extended error codes]. ^The legacy behavior was that [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code and the application would have to make a second call to [sqlite3_reset()] in order to find the underlying cause of the problem. With the "v2" prepare interfaces, the underlying reason for the error is returned immediately. </li> <li> ^If the specific value bound to [parameter \| host parameter] in the WHERE clause might influence the choice of query plan for a statement, then the statement will be automatically recompiled, as if there had been a schema change, on the first [sqlite3_step()] call following any change to the [sqlite3_bind_text \| bindings] of that [parameter]. ^The specific value of WHERE-clause [parameter] might influence the choice of query plan if the parameter is the left-hand side of a [LIKE] or [GLOB] operator or if the parameter is compared to an indexed column and the [SQLITE_ENABLE_STAT3] compile-time option is enabled. </li> ** </ol> / SQLITE_API int SQLITE_STDCALL sqlite3_prepare( sqlite3 db, /* Database handle / const char zSql, /* SQL statement, UTF-8 encoded / int nByte, / Maximum length of zSql in bytes. / sqlite3_stmt ppStmt, / OUT: Statement handle / const char pzTail / OUT: Pointer to unused portion of zSql / ); SQLITE_API int SQLITE_STDCALL sqlite3_prepare_v2( sqlite3 db, /* Database handle / const char zSql, /* SQL statement, UTF-8 encoded / int nByte, / Maximum length of zSql in bytes. / sqlite3_stmt ppStmt, / OUT: Statement handle / const char pzTail / OUT: Pointer to unused portion of zSql / ); SQLITE_API int SQLITE_STDCALL sqlite3_prepare16( sqlite3 db, /* Database handle / const void zSql, /* SQL statement, UTF-16 encoded / int nByte, / Maximum length of zSql in bytes. / sqlite3_stmt ppStmt, / OUT: Statement handle / const void pzTail / OUT: Pointer to unused portion of zSql / ); SQLITE_API int SQLITE_STDCALL sqlite3_prepare16_v2( sqlite3 db, /* Database handle / const void zSql, /* SQL statement, UTF-16 encoded / int nByte, / Maximum length of zSql in bytes. / sqlite3_stmt ppStmt, / OUT: Statement handle / const void pzTail / OUT: Pointer to unused portion of zSql / ); / CAPI3REF: Retrieving Statement SQL METHOD: sqlite3_stmt ^This interface can be used to retrieve a saved copy of the original SQL text used to create a [prepared statement] if that statement was compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()]. / SQLITE_API const char SQLITE_STDCALL sqlite3_sql(sqlite3_stmt pStmt); / CAPI3REF: Determine If An SQL Statement Writes The Database METHOD: sqlite3_stmt ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if and only if the [prepared statement] X makes no direct changes to the content of the database file. Note that [application-defined SQL functions] or [virtual tables] might change the database indirectly as a side effect. ^(For example, if an application defines a function "eval()" that calls [sqlite3_exec()], then the following SQL statement would change the database file through side-effects: <blockquote><pre> SELECT eval('DELETE FROM t1') FROM t2; </pre></blockquote> But because the [SELECT] statement does not change the database file directly, sqlite3_stmt_readonly() would still return true.)^ ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK], [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true, since the statements themselves do not actually modify the database but rather they control the timing of when other statements modify the database. ^The [ATTACH] and [DETACH] statements also cause sqlite3_stmt_readonly() to return true since, while those statements change the configuration of a database connection, they do not make changes to the content of the database files on disk. / SQLITE_API int SQLITE_STDCALL sqlite3_stmt_readonly(sqlite3_stmt pStmt); /* CAPI3REF: Determine If A Prepared Statement Has Been Reset METHOD: sqlite3_stmt ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the [prepared statement] S has been stepped at least once using [sqlite3_step(S)] but has not run to completion and/or has not been reset using [sqlite3_reset(S)]. ^The sqlite3_stmt_busy(S) interface returns false if S is a NULL pointer. If S is not a NULL pointer and is not a pointer to a valid [prepared statement] object, then the behavior is undefined and probably undesirable. This interface can be used in combination [sqlite3_next_stmt()] to locate all prepared statements associated with a database connection that are in need of being reset. This can be used, for example, in diagnostic routines to search for prepared statements that are holding a transaction open. / SQLITE_API int SQLITE_STDCALL sqlite3_stmt_busy(sqlite3_stmt); /* CAPI3REF: Dynamically Typed Value Object KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value} SQLite uses the sqlite3_value object to represent all values that can be stored in a database table. SQLite uses dynamic typing for the values it stores. ^Values stored in sqlite3_value objects can be integers, floating point values, strings, BLOBs, or NULL. An sqlite3_value object may be either "protected" or "unprotected". Some interfaces require a protected sqlite3_value. Other interfaces will accept either a protected or an unprotected sqlite3_value. Every interface that accepts sqlite3_value arguments specifies whether or not it requires a protected sqlite3_value. The terms "protected" and "unprotected" refer to whether or not a mutex is held. An internal mutex is held for a protected sqlite3_value object but no mutex is held for an unprotected sqlite3_value object. If SQLite is compiled to be single-threaded (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0) or if SQLite is run in one of reduced mutex modes [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD] then there is no distinction between protected and unprotected sqlite3_value objects and they can be used interchangeably. However, for maximum code portability it is recommended that applications still make the distinction between protected and unprotected sqlite3_value objects even when not strictly required. ^The sqlite3_value objects that are passed as parameters into the implementation of [application-defined SQL functions] are protected. ^The sqlite3_value object returned by [sqlite3_column_value()] is unprotected. Unprotected sqlite3_value objects may only be used with [sqlite3_result_value()] and [sqlite3_bind_value()]. The [sqlite3_value_blob \| sqlite3_value_type()] family of ** interfaces require protected sqlite3_value objects. / typedef struct Mem sqlite3_value; / CAPI3REF: SQL Function Context Object The context in which an SQL function executes is stored in an sqlite3_context object. ^A pointer to an sqlite3_context object is always first parameter to [application-defined SQL functions]. The application-defined SQL function implementation will pass this pointer through into calls to [sqlite3_result_int \| sqlite3_result()], [sqlite3_aggregate_context()], [sqlite3_user_data()], [sqlite3_context_db_handle()], [sqlite3_get_auxdata()], and/or [sqlite3_set_auxdata()]. / typedef struct sqlite3_context sqlite3_context; / CAPI3REF: Binding Values To Prepared Statements KEYWORDS: {host parameter} {host parameters} {host parameter name} KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding} METHOD: sqlite3_stmt ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants, literals may be replaced by a [parameter] that matches one of following templates: <ul> <li> ? <li> ?NNN <li> :VVV <li> @VVV <li> $VVV </ul> In the templates above, NNN represents an integer literal, and VVV represents an alphanumeric identifier.)^ ^The values of these parameters (also called "host parameter names" or "SQL parameters") ** can be set using the sqlite3_bind_() routines defined here. * ** ^The first argument to the sqlite3_bind_() routines is always * a pointer to the [sqlite3_stmt] object returned from [sqlite3_prepare_v2()] or its variants. ^The second argument is the index of the SQL parameter to be set. ^The leftmost SQL parameter has an index of 1. ^When the same named SQL parameter is used more than once, second and subsequent occurrences have the same index as the first occurrence. ^The index for named parameters can be looked up using the [sqlite3_bind_parameter_index()] API if desired. ^The index for "?NNN" parameters is the value of NNN. ^The NNN value must be between 1 and the [sqlite3_limit()] parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999). ^The third argument is the value to bind to the parameter. ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16() or sqlite3_bind_blob() is a NULL pointer then the fourth parameter is ignored and the end result is the same as sqlite3_bind_null(). ^(In those routines that have a fourth argument, its value is the number of bytes in the parameter. To be clear: the value is the number of <u>bytes</u> in the value, not the number of characters.)^ ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16() is negative, then the length of the string is the number of bytes up to the first zero terminator. If the fourth parameter to sqlite3_bind_blob() is negative, then the behavior is undefined. If a non-negative fourth parameter is provided to sqlite3_bind_text() or sqlite3_bind_text16() or sqlite3_bind_text64() then that parameter must be the byte offset where the NUL terminator would occur assuming the string were NUL terminated. If any NUL characters occur at byte offsets less than the value of the fourth parameter then the resulting string value will contain embedded NULs. The result of expressions involving strings with embedded NULs is undefined. ^The fifth argument to the BLOB and string binding interfaces is a destructor used to dispose of the BLOB or string after SQLite has finished with it. ^The destructor is called to dispose of the BLOB or string even if the call to bind API fails. ^If the fifth argument is the special value [SQLITE_STATIC], then SQLite assumes that the information is in static, unmanaged space and does not need to be freed. ^If the fifth argument has the value [SQLITE_TRANSIENT], then SQLite makes its own private copy of the data immediately, before the sqlite3_bind_() routine returns. * ^The sixth argument to sqlite3_bind_text64() must be one of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE] to specify the encoding of the text in the third parameter. If the sixth argument to sqlite3_bind_text64() is not one of the allowed values shown above, or if the text encoding is different from the encoding specified by the sixth parameter, then the behavior is undefined. ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that is filled with zeroes. ^A zeroblob uses a fixed amount of memory (just an integer to hold its size) while it is being processed. Zeroblobs are intended to serve as placeholders for BLOBs whose content is later written using [sqlite3_blob_open \| incremental BLOB I/O] routines. ^A negative value for the zeroblob results in a zero-length BLOB. ** ^If any of the sqlite3_bind_() routines are called with a NULL pointer * for the [prepared statement] or with a prepared statement for which [sqlite3_step()] has been called more recently than [sqlite3_reset()], then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_() routine is passed a [prepared statement] that has been finalized, the result is undefined and probably harmful. ^Bindings are not cleared by the [sqlite3_reset()] routine. ^Unbound parameters are interpreted as NULL. ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an [error code] if anything goes wrong. ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or [SQLITE_MAX_LENGTH]. ^[SQLITE_RANGE] is returned if the parameter index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails. See also: [sqlite3_bind_parameter_count()], ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()]. / SQLITE_API int SQLITE_STDCALL sqlite3_bind_blob(sqlite3_stmt, int, const void, int n, void()(void)); SQLITE_API int SQLITE_STDCALL sqlite3_bind_blob64(sqlite3_stmt, int, const void, sqlite3_uint64, void()(void)); SQLITE_API int SQLITE_STDCALL sqlite3_bind_double(sqlite3_stmt, int, double); SQLITE_API int SQLITE_STDCALL sqlite3_bind_int(sqlite3_stmt, int, int); SQLITE_API int SQLITE_STDCALL sqlite3_bind_int64(sqlite3_stmt, int, sqlite3_int64); SQLITE_API int SQLITE_STDCALL sqlite3_bind_null(sqlite3_stmt, int); SQLITE_API int SQLITE_STDCALL sqlite3_bind_text(sqlite3_stmt,int,const char,int,void()(void)); SQLITE_API int SQLITE_STDCALL sqlite3_bind_text16(sqlite3_stmt, int, const void, int, void()(void)); SQLITE_API int SQLITE_STDCALL sqlite3_bind_text64(sqlite3_stmt, int, const char, sqlite3_uint64, void()(void), unsigned char encoding); SQLITE_API int SQLITE_STDCALL sqlite3_bind_value(sqlite3_stmt, int, const sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_bind_zeroblob(sqlite3_stmt, int, int n); /* CAPI3REF: Number Of SQL Parameters METHOD: sqlite3_stmt ^This routine can be used to find the number of [SQL parameters] in a [prepared statement]. SQL parameters are tokens of the form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as placeholders for values that are [sqlite3_bind_blob \| bound] to the parameters at a later time. ^(This routine actually returns the index of the largest (rightmost) parameter. For all forms except ?NNN, this will correspond to the number of unique parameters. If parameters of the ?NNN form are used, there may be gaps in the list.)^ See also: [sqlite3_bind_blob\|sqlite3_bind()], [sqlite3_bind_parameter_name()], and ** [sqlite3_bind_parameter_index()]. / SQLITE_API int SQLITE_STDCALL sqlite3_bind_parameter_count(sqlite3_stmt); /* CAPI3REF: Name Of A Host Parameter METHOD: sqlite3_stmt ^The sqlite3_bind_parameter_name(P,N) interface returns the name of the N-th [SQL parameter] in the [prepared statement] P. ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA" have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA" respectively. In other words, the initial ":" or "$" or "@" or "?" is included as part of the name.)^ ^Parameters of the form "?" without a following integer have no name and are referred to as "nameless" or "anonymous parameters". ^The first host parameter has an index of 1, not 0. ^If the value N is out of range or if the N-th parameter is nameless, then NULL is returned. ^The returned string is always in UTF-8 encoding even if the named parameter was originally specified as UTF-16 in [sqlite3_prepare16()] or [sqlite3_prepare16_v2()]. See also: [sqlite3_bind_blob\|sqlite3_bind()], [sqlite3_bind_parameter_count()], and [sqlite3_bind_parameter_index()]. / SQLITE_API const char SQLITE_STDCALL sqlite3_bind_parameter_name(sqlite3_stmt, int); / CAPI3REF: Index Of A Parameter With A Given Name METHOD: sqlite3_stmt ^Return the index of an SQL parameter given its name. ^The index value returned is suitable for use as the second parameter to [sqlite3_bind_blob\|sqlite3_bind()]. ^A zero is returned if no matching parameter is found. ^The parameter name must be given in UTF-8 even if the original statement was prepared from UTF-16 text using [sqlite3_prepare16_v2()]. See also: [sqlite3_bind_blob\|sqlite3_bind()], [sqlite3_bind_parameter_count()], and ** [sqlite3_bind_parameter_index()]. / SQLITE_API int SQLITE_STDCALL sqlite3_bind_parameter_index(sqlite3_stmt, const char zName); / CAPI3REF: Reset All Bindings On A Prepared Statement METHOD: sqlite3_stmt ^Contrary to the intuition of many, [sqlite3_reset()] does not reset the [sqlite3_bind_blob \| bindings] on a [prepared statement]. ^Use this routine to reset all host parameters to NULL. / SQLITE_API int SQLITE_STDCALL sqlite3_clear_bindings(sqlite3_stmt); /* CAPI3REF: Number Of Columns In A Result Set METHOD: sqlite3_stmt ^Return the number of columns in the result set returned by the [prepared statement]. ^This routine returns 0 if pStmt is an SQL statement that does not return data (for example an [UPDATE]). See also: [sqlite3_data_count()] / SQLITE_API int SQLITE_STDCALL sqlite3_column_count(sqlite3_stmt pStmt); /* CAPI3REF: Column Names In A Result Set METHOD: sqlite3_stmt ^These routines return the name assigned to a particular column in the result set of a [SELECT] statement. ^The sqlite3_column_name() interface returns a pointer to a zero-terminated UTF-8 string and sqlite3_column_name16() returns a pointer to a zero-terminated UTF-16 string. ^The first parameter is the [prepared statement] that implements the [SELECT] statement. ^The second parameter is the column number. ^The leftmost column is number 0. ^The returned string pointer is valid until either the [prepared statement] is destroyed by [sqlite3_finalize()] or until the statement is automatically reprepared by the first call to [sqlite3_step()] for a particular run or until the next call to sqlite3_column_name() or sqlite3_column_name16() on the same column. ^If sqlite3_malloc() fails during the processing of either routine (for example during a conversion from UTF-8 to UTF-16) then a NULL pointer is returned. ^The name of a result column is the value of the "AS" clause for that column, if there is an AS clause. If there is no AS clause then the name of the column is unspecified and may change from ** one release of SQLite to the next. / SQLITE_API const char SQLITE_STDCALL sqlite3_column_name(sqlite3_stmt, int N); SQLITE_API const void SQLITE_STDCALL sqlite3_column_name16(sqlite3_stmt, int N); / CAPI3REF: Source Of Data In A Query Result METHOD: sqlite3_stmt ^These routines provide a means to determine the database, table, and table column that is the origin of a particular result column in [SELECT] statement. ^The name of the database or table or column can be returned as either a UTF-8 or UTF-16 string. ^The _database_ routines return the database name, the _table_ routines return the table name, and the origin_ routines return the column name. ^The returned string is valid until the [prepared statement] is destroyed using [sqlite3_finalize()] or until the statement is automatically reprepared by the first call to [sqlite3_step()] for a particular run or until the same information is requested again in a different encoding. ^The names returned are the original un-aliased names of the database, table, and column. ^The first argument to these interfaces is a [prepared statement]. ^These functions return information about the Nth result column returned by the statement, where N is the second function argument. ^The left-most column is column 0 for these routines. ^If the Nth column returned by the statement is an expression or subquery and is not a column value, then all of these functions return NULL. ^These routine might also return NULL if a memory allocation error occurs. ^Otherwise, they return the name of the attached database, table, or column that query result column was extracted from. ^As with all other SQLite APIs, those whose names end with "16" return UTF-16 encoded strings and the other functions return UTF-8. ^These APIs are only available if the library was compiled with the [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol. If two or more threads call one or more of these routines against the same prepared statement and column at the same time then the results are undefined. If two or more threads call one or more [sqlite3_column_database_name \| column metadata interfaces] for the same [prepared statement] and result column at the same time then the results are undefined. / SQLITE_API const char SQLITE_STDCALL sqlite3_column_database_name(sqlite3_stmt,int); SQLITE_API const void SQLITE_STDCALL sqlite3_column_database_name16(sqlite3_stmt,int); SQLITE_API const char SQLITE_STDCALL sqlite3_column_table_name(sqlite3_stmt,int); SQLITE_API const void SQLITE_STDCALL sqlite3_column_table_name16(sqlite3_stmt,int); SQLITE_API const char SQLITE_STDCALL sqlite3_column_origin_name(sqlite3_stmt,int); SQLITE_API const void SQLITE_STDCALL sqlite3_column_origin_name16(sqlite3_stmt,int); / CAPI3REF: Declared Datatype Of A Query Result METHOD: sqlite3_stmt ^(The first parameter is a [prepared statement]. If this statement is a [SELECT] statement and the Nth column of the returned result set of that [SELECT] is a table column (not an expression or subquery) then the declared type of the table column is returned.)^ ^If the Nth column of the result set is an expression or subquery, then a NULL pointer is returned. ^The returned string is always UTF-8 encoded. ^(For example, given the database schema: CREATE TABLE t1(c1 VARIANT); and the following statement to be compiled: SELECT c1 + 1, c1 FROM t1; this routine would return the string "VARIANT" for the second result column (i==1), and a NULL pointer for the first result column (i==0).)^ ^SQLite uses dynamic run-time typing. ^So just because a column is declared to contain a particular type does not mean that the data stored in that column is of the declared type. SQLite is strongly typed, but the typing is dynamic not static. ^Type is associated with individual values, not with the containers used to hold those values. / SQLITE_API const char SQLITE_STDCALL sqlite3_column_decltype(sqlite3_stmt,int); SQLITE_API const void SQLITE_STDCALL sqlite3_column_decltype16(sqlite3_stmt,int); / CAPI3REF: Evaluate An SQL Statement METHOD: sqlite3_stmt After a [prepared statement] has been prepared using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function must be called one or more times to evaluate the statement. The details of the behavior of the sqlite3_step() interface depend on whether the statement was prepared using the newer "v2" interface [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy interface [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the new "v2" interface is recommended for new applications but the legacy interface will continue to be supported. ^In the legacy interface, the return value will be either [SQLITE_BUSY], [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE]. ^With the "v2" interface, any of the other [result codes] or [extended result codes] might be returned as well. ^[SQLITE_BUSY] means that the database engine was unable to acquire the database locks it needs to do its job. ^If the statement is a [COMMIT] or occurs outside of an explicit transaction, then you can retry the statement. If the statement is not a [COMMIT] and occurs within an explicit transaction then you should rollback the transaction before continuing. ^[SQLITE_DONE] means that the statement has finished executing successfully. sqlite3_step() should not be called again on this virtual machine without first calling [sqlite3_reset()] to reset the virtual machine back to its initial state. ^If the SQL statement being executed returns any data, then [SQLITE_ROW] is returned each time a new row of data is ready for processing by the caller. The values may be accessed using the [column access functions]. sqlite3_step() is called again to retrieve the next row of data. ^[SQLITE_ERROR] means that a run-time error (such as a constraint violation) has occurred. sqlite3_step() should not be called again on the VM. More information may be found by calling [sqlite3_errmsg()]. ^With the legacy interface, a more specific error code (for example, [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth) can be obtained by calling [sqlite3_reset()] on the [prepared statement]. ^In the "v2" interface, the more specific error code is returned directly by sqlite3_step(). [SQLITE_MISUSE] means that the this routine was called inappropriately. Perhaps it was called on a [prepared statement] that has already been [sqlite3_finalize \| finalized] or on one that had previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could be the case that the same database connection is being used by two or more threads at the same moment in time. For all versions of SQLite up to and including 3.6.23.1, a call to [sqlite3_reset()] was required after sqlite3_step() returned anything other than [SQLITE_ROW] before any subsequent invocation of sqlite3_step(). Failure to reset the prepared statement using [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from sqlite3_step(). But after version 3.6.23.1, sqlite3_step() began calling [sqlite3_reset()] automatically in this circumstance rather than returning [SQLITE_MISUSE]. This is not considered a compatibility break because any application that ever receives an SQLITE_MISUSE error is broken by definition. The [SQLITE_OMIT_AUTORESET] compile-time option can be used to restore the legacy behavior. <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step() API always returns a generic error code, [SQLITE_ERROR], following any error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the specific [error codes] that better describes the error. We admit that this is a goofy design. The problem has been fixed with the "v2" interface. If you prepare all of your SQL statements using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces, then the more specific [error codes] are returned directly by sqlite3_step(). The use of the "v2" interface is recommended. / SQLITE_API int SQLITE_STDCALL sqlite3_step(sqlite3_stmt); /* CAPI3REF: Number of columns in a result set METHOD: sqlite3_stmt ^The sqlite3_data_count(P) interface returns the number of columns in the current row of the result set of [prepared statement] P. ^If prepared statement P does not have results ready to return ** (via calls to the [sqlite3_column_int \| sqlite3_column_()] of * interfaces) then sqlite3_data_count(P) returns 0. ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer. ^The sqlite3_data_count(P) routine returns 0 if the previous call to [sqlite3_step](P) returned [SQLITE_DONE]. ^The sqlite3_data_count(P) will return non-zero if previous call to [sqlite3_step](P) returned [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum] where it always returns zero since each step of that multi-step pragma returns 0 columns of data. ** See also: [sqlite3_column_count()] / SQLITE_API int SQLITE_STDCALL sqlite3_data_count(sqlite3_stmt pStmt); /* CAPI3REF: Fundamental Datatypes KEYWORDS: SQLITE_TEXT ^(Every value in SQLite has one of five fundamental datatypes: <ul> <li> 64-bit signed integer <li> 64-bit IEEE floating point number <li> string <li> BLOB <li> NULL </ul>)^ These constants are codes for each of those types. Note that the SQLITE_TEXT constant was also used in SQLite version 2 for a completely different meaning. Software that links against both SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not ** SQLITE_TEXT. / #define SQLITE_INTEGER 1 #define SQLITE_FLOAT 2 #define SQLITE_BLOB 4 #define SQLITE_NULL 5 #ifdef SQLITE_TEXT # undef SQLITE_TEXT #else # define SQLITE_TEXT 3 #endif #define SQLITE3_TEXT 3 / CAPI3REF: Result Values From A Query KEYWORDS: {column access functions} METHOD: sqlite3_stmt These routines form the "result set" interface. ^These routines return information about a single column of the current result row of a query. ^In every case the first argument is a pointer ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt] * that was returned from [sqlite3_prepare_v2()] or one of its variants) and the second argument is the index of the column for which information should be returned. ^The leftmost column of the result set has the index 0. ^The number of columns in the result can be determined using [sqlite3_column_count()]. If the SQL statement does not currently point to a valid row, or if the column index is out of range, the result is undefined. These routines may only be called when the most recent call to [sqlite3_step()] has returned [SQLITE_ROW] and neither [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently. If any of these routines are called after [sqlite3_reset()] or [sqlite3_finalize()] or after [sqlite3_step()] has returned something other than [SQLITE_ROW], the results are undefined. If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()] are called from a different thread while any of these routines are pending, then the results are undefined. ^The sqlite3_column_type() routine returns the [SQLITE_INTEGER \| datatype code] for the initial data type of the result column. ^The returned value is one of [SQLITE_INTEGER], [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL]. The value returned by sqlite3_column_type() is only meaningful if no type conversions have occurred as described below. After a type conversion, the value returned by sqlite3_column_type() is undefined. Future versions of SQLite may change the behavior of sqlite3_column_type() following a type conversion. ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes() routine returns the number of bytes in that BLOB or string. ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts the string to UTF-8 and then returns the number of bytes. ^If the result is a numeric value then sqlite3_column_bytes() uses [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns the number of bytes in that string. ^If the result is NULL, then sqlite3_column_bytes() returns zero. ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16() routine returns the number of bytes in that BLOB or string. ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts the string to UTF-16 and then returns the number of bytes. ^If the result is a numeric value then sqlite3_column_bytes16() uses [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns the number of bytes in that string. ^If the result is NULL, then sqlite3_column_bytes16() returns zero. ^The values returned by [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] do not include the zero terminators at the end of the string. ^For clarity: the values returned by [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of bytes in the string, not the number of characters. ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(), even empty strings, are always zero-terminated. ^The return value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer. ^The object returned by [sqlite3_column_value()] is an [unprotected sqlite3_value] object. An unprotected sqlite3_value object may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()]. If the [unprotected sqlite3_value] object returned by [sqlite3_column_value()] is used in any other way, including calls to routines like [sqlite3_value_int()], [sqlite3_value_text()], or [sqlite3_value_bytes()], then the behavior is undefined. These routines attempt to convert the value where appropriate. ^For example, if the internal representation is FLOAT and a text result is requested, [sqlite3_snprintf()] is used internally to perform the conversion automatically. ^(The following table details the conversions that are applied: <blockquote> <table border="1"> <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion <tr><td> NULL <td> INTEGER <td> Result is 0 <tr><td> NULL <td> FLOAT <td> Result is 0.0 <tr><td> NULL <td> TEXT <td> Result is a NULL pointer <tr><td> NULL <td> BLOB <td> Result is a NULL pointer <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT <tr><td> FLOAT <td> INTEGER <td> [CAST] to INTEGER <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float <tr><td> FLOAT <td> BLOB <td> [CAST] to BLOB <tr><td> TEXT <td> INTEGER <td> [CAST] to INTEGER <tr><td> TEXT <td> FLOAT <td> [CAST] to REAL <tr><td> TEXT <td> BLOB <td> No change <tr><td> BLOB <td> INTEGER <td> [CAST] to INTEGER <tr><td> BLOB <td> FLOAT <td> [CAST] to REAL <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed </table> </blockquote>)^ The table above makes reference to standard C library functions atoi() and atof(). SQLite does not really use these functions. It has its own equivalent internal routines. The atoi() and atof() names are used in the table for brevity and because they are familiar to most C programmers. Note that when type conversions occur, pointers returned by prior calls to sqlite3_column_blob(), sqlite3_column_text(), and/or sqlite3_column_text16() may be invalidated. Type conversions and pointer invalidations might occur in the following cases: <ul> <li> The initial content is a BLOB and sqlite3_column_text() or sqlite3_column_text16() is called. A zero-terminator might need to be added to the string.</li> <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or sqlite3_column_text16() is called. The content must be converted to UTF-16.</li> <li> The initial content is UTF-16 text and sqlite3_column_bytes() or sqlite3_column_text() is called. The content must be converted to UTF-8.</li> </ul> ^Conversions between UTF-16be and UTF-16le are always done in place and do not invalidate a prior pointer, though of course the content of the buffer that the prior pointer references will have been modified. Other kinds of conversion are done in place when it is possible, but sometimes they are not possible and in those cases prior pointers are invalidated. The safest and easiest to remember policy is to invoke these routines in one of the following ways: <ul> <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li> <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li> <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li> </ul> In other words, you should call sqlite3_column_text(), sqlite3_column_blob(), or sqlite3_column_text16() first to force the result into the desired format, then invoke sqlite3_column_bytes() or sqlite3_column_bytes16() to find the size of the result. Do not mix calls to sqlite3_column_text() or sqlite3_column_blob() with calls to sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16() with calls to sqlite3_column_bytes(). ^The pointers returned are valid until a type conversion occurs as described above, or until [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()] is called. ^The memory space used to hold strings and BLOBs is freed automatically. Do <b>not</b> pass the pointers returned from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into [sqlite3_free()]. ^(If a memory allocation error occurs during the evaluation of any of these routines, a default value is returned. The default value is either the integer 0, the floating point number 0.0, or a NULL pointer. Subsequent calls to [sqlite3_errcode()] will return ** [SQLITE_NOMEM].)^ / SQLITE_API const void SQLITE_STDCALL sqlite3_column_blob(sqlite3_stmt, int iCol); SQLITE_API int SQLITE_STDCALL sqlite3_column_bytes(sqlite3_stmt, int iCol); SQLITE_API int SQLITE_STDCALL sqlite3_column_bytes16(sqlite3_stmt, int iCol); SQLITE_API double SQLITE_STDCALL sqlite3_column_double(sqlite3_stmt, int iCol); SQLITE_API int SQLITE_STDCALL sqlite3_column_int(sqlite3_stmt, int iCol); SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_column_int64(sqlite3_stmt, int iCol); SQLITE_API const unsigned char SQLITE_STDCALL sqlite3_column_text(sqlite3_stmt, int iCol); SQLITE_API const void SQLITE_STDCALL sqlite3_column_text16(sqlite3_stmt, int iCol); SQLITE_API int SQLITE_STDCALL sqlite3_column_type(sqlite3_stmt, int iCol); SQLITE_API sqlite3_value SQLITE_STDCALL sqlite3_column_value(sqlite3_stmt, int iCol); / CAPI3REF: Destroy A Prepared Statement Object DESTRUCTOR: sqlite3_stmt ^The sqlite3_finalize() function is called to delete a [prepared statement]. ^If the most recent evaluation of the statement encountered no errors or if the statement is never been evaluated, then sqlite3_finalize() returns SQLITE_OK. ^If the most recent evaluation of statement S failed, then sqlite3_finalize(S) returns the appropriate [error code] or [extended error code]. ^The sqlite3_finalize(S) routine can be called at any point during the life cycle of [prepared statement] S: before statement S is ever evaluated, after one or more calls to [sqlite3_reset()], or after any call to [sqlite3_step()] regardless of whether or not the statement has completed execution. ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op. The application must finalize every [prepared statement] in order to avoid resource leaks. It is a grievous error for the application to try to use a prepared statement after it has been finalized. Any use of a prepared statement after it has been finalized can result in undefined and undesirable behavior such as segfaults and heap corruption. / SQLITE_API int SQLITE_STDCALL sqlite3_finalize(sqlite3_stmt pStmt); /* CAPI3REF: Reset A Prepared Statement Object METHOD: sqlite3_stmt The sqlite3_reset() function is called to reset a [prepared statement] object back to its initial state, ready to be re-executed. ^Any SQL statement variables that had values bound to them using ** the [sqlite3_bind_blob \| sqlite3_bind_() API] retain their values. * Use [sqlite3_clear_bindings()] to reset the bindings. ^The [sqlite3_reset(S)] interface resets the [prepared statement] S back to the beginning of its program. ^If the most recent call to [sqlite3_step(S)] for the [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE], or if [sqlite3_step(S)] has never before been called on S, then [sqlite3_reset(S)] returns [SQLITE_OK]. ^If the most recent call to [sqlite3_step(S)] for the [prepared statement] S indicated an error, then [sqlite3_reset(S)] returns an appropriate [error code]. ^The [sqlite3_reset(S)] interface does not change the values ** of any [sqlite3_bind_blob\|bindings] on the [prepared statement] S. / SQLITE_API int SQLITE_STDCALL sqlite3_reset(sqlite3_stmt pStmt); /* CAPI3REF: Create Or Redefine SQL Functions KEYWORDS: {function creation routines} KEYWORDS: {application-defined SQL function} KEYWORDS: {application-defined SQL functions} METHOD: sqlite3 ^These functions (collectively known as "function creation routines") are used to add SQL functions or aggregates or to redefine the behavior of existing SQL functions or aggregates. The only differences between these routines are the text encoding expected for the second parameter (the name of the function being created) and the presence or absence of a destructor callback for the application data pointer. ^The first parameter is the [database connection] to which the SQL function is to be added. ^If an application uses more than one database connection then application-defined SQL functions must be added to each database connection separately. ^The second parameter is the name of the SQL function to be created or redefined. ^The length of the name is limited to 255 bytes in a UTF-8 representation, exclusive of the zero-terminator. ^Note that the name length limit is in UTF-8 bytes, not characters nor UTF-16 bytes. ^Any attempt to create a function with a longer name will result in [SQLITE_MISUSE] being returned. ^The third parameter (nArg) is the number of arguments that the SQL function or aggregate takes. ^If this parameter is -1, then the SQL function or aggregate may take any number of arguments between 0 and the limit set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third parameter is less than -1 or greater than 127 then the behavior is undefined. ^The fourth parameter, eTextRep, specifies what [SQLITE_UTF8 \| text encoding] this SQL function prefers for its parameters. The application should set this parameter to [SQLITE_UTF16LE] if the function implementation invokes [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the implementation invokes [sqlite3_value_text16be()] on an input, or [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8] otherwise. ^The same SQL function may be registered multiple times using different preferred text encodings, with different implementations for each encoding. ^When multiple implementations of the same function are available, SQLite will pick the one that involves the least amount of data conversion. ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC] to signal that the function will always return the same result given the same inputs within a single SQL statement. Most SQL functions are deterministic. The built-in [random()] SQL function is an example of a function that is not deterministic. The SQLite query planner is able to perform additional optimizations on deterministic functions, so use of the [SQLITE_DETERMINISTIC] flag is recommended where possible. ^(The fifth parameter is an arbitrary pointer. The implementation of the function can gain access to this pointer using [sqlite3_user_data()].)^ ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are pointers to C-language functions that implement the SQL function or aggregate. ^A scalar SQL function requires an implementation of the xFunc callback only; NULL pointers must be passed as the xStep and xFinal parameters. ^An aggregate SQL function requires an implementation of xStep and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing SQL function or aggregate, pass NULL pointers for all three function callbacks. ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL, then it is destructor for the application data pointer. The destructor is invoked when the function is deleted, either by being overloaded or when the database connection closes.)^ ^The destructor is also invoked if the call to sqlite3_create_function_v2() fails. ^When the destructor callback of the tenth parameter is invoked, it is passed a single argument which is a copy of the application data pointer which was the fifth parameter to sqlite3_create_function_v2(). ^It is permitted to register multiple implementations of the same functions with the same name but with either differing numbers of arguments or differing preferred text encodings. ^SQLite will use the implementation that most closely matches the way in which the SQL function is used. ^A function implementation with a non-negative nArg parameter is a better match than a function implementation with a negative nArg. ^A function where the preferred text encoding matches the database encoding is a better match than a function where the encoding is different. ^A function where the encoding difference is between UTF16le and UTF16be is a closer match than a function where the encoding difference is between UTF8 and UTF16. ^Built-in functions may be overloaded by new application-defined functions. ^An application-defined function is permitted to call other SQLite interfaces. However, such calls must not close the database connection nor finalize or reset the prepared statement in which the function is running. / SQLITE_API int SQLITE_STDCALL sqlite3_create_function( sqlite3 db, const char zFunctionName, int nArg, int eTextRep, void pApp, void (xFunc)(sqlite3_context,int,sqlite3_value*), void (xStep)(sqlite3_context,int,sqlite3_value), void (xFinal)(sqlite3_context) ); SQLITE_API int SQLITE_STDCALL sqlite3_create_function16( sqlite3 db, const void zFunctionName, int nArg, int eTextRep, void pApp, void (xFunc)(sqlite3_context,int,sqlite3_value*), void (xStep)(sqlite3_context,int,sqlite3_value), void (xFinal)(sqlite3_context) ); SQLITE_API int SQLITE_STDCALL sqlite3_create_function_v2( sqlite3 db, const char zFunctionName, int nArg, int eTextRep, void pApp, void (xFunc)(sqlite3_context,int,sqlite3_value*), void (xStep)(sqlite3_context,int,sqlite3_value), void (xFinal)(sqlite3_context), void(xDestroy)(void) ); / CAPI3REF: Text Encodings These constant define integer codes that represent the various text encodings supported by SQLite. / #define SQLITE_UTF8 1 / IMP: R-37514-35566 / #define SQLITE_UTF16LE 2 / IMP: R-03371-37637 / #define SQLITE_UTF16BE 3 / IMP: R-51971-34154 / #define SQLITE_UTF16 4 / Use native byte order / #define SQLITE_ANY 5 / Deprecated / #define SQLITE_UTF16_ALIGNED 8 / sqlite3_create_collation only / / CAPI3REF: Function Flags These constants may be ORed together with the [SQLITE_UTF8 \| preferred text encoding] as the fourth argument to [sqlite3_create_function()], [sqlite3_create_function16()], or [sqlite3_create_function_v2()]. / #define SQLITE_DETERMINISTIC 0x800 / CAPI3REF: Deprecated Functions DEPRECATED These functions are [deprecated]. In order to maintain backwards compatibility with older code, these functions continue to be supported. However, new applications should avoid the use of these functions. To encourage programmers to avoid these functions, we will not explain what they do. / #ifndef SQLITE_OMIT_DEPRECATED SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_aggregate_count(sqlite3_context); SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_expired(sqlite3_stmt); SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_transfer_bindings(sqlite3_stmt, sqlite3_stmt); SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_global_recover(void); SQLITE_API SQLITE_DEPRECATED void SQLITE_STDCALL sqlite3_thread_cleanup(void); SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_memory_alarm(void()(void,sqlite3_int64,int), void,sqlite3_int64); #endif /* CAPI3REF: Obtaining SQL Function Parameter Values METHOD: sqlite3_value The C-language implementation of SQL functions and aggregates uses this set of interface routines to access the parameter values on the function or aggregate. The xFunc (for scalar functions) or xStep (for aggregates) parameters to [sqlite3_create_function()] and [sqlite3_create_function16()] define callbacks that implement the SQL functions and aggregates. The 3rd parameter to these callbacks is an array of pointers to [protected sqlite3_value] objects. There is one [sqlite3_value] object for each parameter to the SQL function. These routines are used to extract values from the [sqlite3_value] objects. These routines work only with [protected sqlite3_value] objects. Any attempt to use these routines on an [unprotected sqlite3_value] object results in undefined behavior. ^These routines work just like the corresponding [column access functions] except that these routines take a single [protected sqlite3_value] object pointer instead of a [sqlite3_stmt] pointer and an integer column number. * ^The sqlite3_value_text16() interface extracts a UTF-16 string in the native byte-order of the host machine. ^The sqlite3_value_text16be() and sqlite3_value_text16le() interfaces extract UTF-16 strings as big-endian and little-endian respectively. ^(The sqlite3_value_numeric_type() interface attempts to apply numeric affinity to the value. This means that an attempt is made to convert the value to an integer or floating point. If such a conversion is possible without loss of information (in other words, if the value is a string that looks like a number) then the conversion is performed. Otherwise no conversion occurs. The [SQLITE_INTEGER \| datatype] after conversion is returned.)^ Please pay particular attention to the fact that the pointer returned from [sqlite3_value_blob()], [sqlite3_value_text()], or [sqlite3_value_text16()] can be invalidated by a subsequent call to [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()], or [sqlite3_value_text16()]. These routines must be called from the same thread as ** the SQL function that supplied the [sqlite3_value] parameters. / SQLITE_API const void SQLITE_STDCALL sqlite3_value_blob(sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_value_bytes(sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_value_bytes16(sqlite3_value); SQLITE_API double SQLITE_STDCALL sqlite3_value_double(sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_value_int(sqlite3_value); SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_value_int64(sqlite3_value); SQLITE_API const unsigned char SQLITE_STDCALL sqlite3_value_text(sqlite3_value); SQLITE_API const void SQLITE_STDCALL sqlite3_value_text16(sqlite3_value); SQLITE_API const void SQLITE_STDCALL sqlite3_value_text16le(sqlite3_value); SQLITE_API const void SQLITE_STDCALL sqlite3_value_text16be(sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_value_type(sqlite3_value); SQLITE_API int SQLITE_STDCALL sqlite3_value_numeric_type(sqlite3_value); / CAPI3REF: Obtain Aggregate Function Context METHOD: sqlite3_context Implementations of aggregate SQL functions use this routine to allocate memory for storing their state. ^The first time the sqlite3_aggregate_context(C,N) routine is called for a particular aggregate function, SQLite allocates N of memory, zeroes out that memory, and returns a pointer to the new memory. ^On second and subsequent calls to sqlite3_aggregate_context() for the same aggregate function instance, the same buffer is returned. Sqlite3_aggregate_context() is normally called once for each invocation of the xStep callback and then one last time when the xFinal callback is invoked. ^(When no rows match an aggregate query, the xStep() callback of the aggregate function implementation is never called and xFinal() is called exactly once. In those cases, sqlite3_aggregate_context() might be called for the first time from within xFinal().)^ ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer when first called if N is less than or equal to zero or if a memory allocate error occurs. ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is determined by the N parameter on first successful call. Changing the value of N in subsequent call to sqlite3_aggregate_context() within the same aggregate function instance will not resize the memory allocation.)^ Within the xFinal callback, it is customary to set N=0 in calls to sqlite3_aggregate_context(C,N) so that no pointless memory allocations occur. ^SQLite automatically frees the memory allocated by sqlite3_aggregate_context() when the aggregate query concludes. The first parameter must be a copy of the [sqlite3_context \| SQL function context] that is the first parameter to the xStep or xFinal callback routine that implements the aggregate function. This routine must be called from the same thread in which ** the aggregate SQL function is running. / SQLITE_API void SQLITE_STDCALL sqlite3_aggregate_context(sqlite3_context, int nBytes); / CAPI3REF: User Data For Functions METHOD: sqlite3_context ^The sqlite3_user_data() interface returns a copy of the pointer that was the pUserData parameter (the 5th parameter) of the [sqlite3_create_function()] and [sqlite3_create_function16()] routines that originally registered the application defined function. This routine must be called from the same thread in which ** the application-defined function is running. / SQLITE_API void SQLITE_STDCALL sqlite3_user_data(sqlite3_context); / CAPI3REF: Database Connection For Functions METHOD: sqlite3_context ^The sqlite3_context_db_handle() interface returns a copy of the pointer to the [database connection] (the 1st parameter) of the [sqlite3_create_function()] and [sqlite3_create_function16()] routines that originally registered the application defined function. / SQLITE_API sqlite3 SQLITE_STDCALL sqlite3_context_db_handle(sqlite3_context); / CAPI3REF: Function Auxiliary Data METHOD: sqlite3_context These functions may be used by (non-aggregate) SQL functions to associate metadata with argument values. If the same value is passed to multiple invocations of the same SQL function during query execution, under some circumstances the associated metadata may be preserved. An example of where this might be useful is in a regular-expression matching function. The compiled version of the regular expression can be stored as metadata associated with the pattern string. Then as long as the pattern string remains the same, the compiled regular expression can be reused on multiple invocations of the same function. ^The sqlite3_get_auxdata() interface returns a pointer to the metadata associated by the sqlite3_set_auxdata() function with the Nth argument value to the application-defined function. ^If there is no metadata associated with the function argument, this sqlite3_get_auxdata() interface returns a NULL pointer. ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th argument of the application-defined function. ^Subsequent calls to sqlite3_get_auxdata(C,N) return P from the most recent sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or NULL if the metadata has been discarded. ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL, SQLite will invoke the destructor function X with parameter P exactly once, when the metadata is discarded. SQLite is free to discard the metadata at any time, including: <ul> <li> when the corresponding function parameter changes, or <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the SQL statement, or <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or <li> during the original sqlite3_set_auxdata() call when a memory allocation error occurs. </ul>)^ Note the last bullet in particular. The destructor X in sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the sqlite3_set_auxdata() interface even returns. Hence sqlite3_set_auxdata() should be called near the end of the function implementation and the function implementation should not make any use of P after sqlite3_set_auxdata() has been called. ^(In practice, metadata is preserved between function calls for function parameters that are compile-time constants, including literal values and [parameters] and expressions composed from the same.)^ These routines must be called from the same thread in which ** the SQL function is running. / SQLITE_API void SQLITE_STDCALL sqlite3_get_auxdata(sqlite3_context, int N); SQLITE_API void SQLITE_STDCALL sqlite3_set_auxdata(sqlite3_context, int N, void, void ()(void)); / CAPI3REF: Constants Defining Special Destructor Behavior These are special values for the destructor that is passed in as the final argument to routines like [sqlite3_result_blob()]. ^If the destructor argument is SQLITE_STATIC, it means that the content pointer is constant and will never change. It does not need to be destroyed. ^The SQLITE_TRANSIENT value means that the content will likely change in the near future and that SQLite should make its own private copy of the content before returning. The typedef is necessary to work around problems in certain C++ compilers. / typedef void (sqlite3_destructor_type)(void); #define SQLITE_STATIC ((sqlite3_destructor_type)0) #define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1) / CAPI3REF: Setting The Result Of An SQL Function METHOD: sqlite3_context These routines are used by the xFunc or xFinal callbacks that implement SQL functions and aggregates. See [sqlite3_create_function()] and [sqlite3_create_function16()] for additional information. These functions work very much like the [parameter binding] family of functions used to bind values to host parameters in prepared statements. Refer to the [SQL parameter] documentation for additional information. ^The sqlite3_result_blob() interface sets the result from an application-defined function to be the BLOB whose content is pointed to by the second parameter and which is N bytes long where N is the third parameter. ^The sqlite3_result_zeroblob() interfaces set the result of the application-defined function to be a BLOB containing all zero bytes and N bytes in size, where N is the value of the 2nd parameter. ^The sqlite3_result_double() interface sets the result from an application-defined function to be a floating point value specified by its 2nd argument. ^The sqlite3_result_error() and sqlite3_result_error16() functions cause the implemented SQL function to throw an exception. ^SQLite uses the string pointed to by the 2nd parameter of sqlite3_result_error() or sqlite3_result_error16() as the text of an error message. ^SQLite interprets the error message string from sqlite3_result_error() as UTF-8. ^SQLite interprets the string from sqlite3_result_error16() as UTF-16 in native byte order. ^If the third parameter to sqlite3_result_error() or sqlite3_result_error16() is negative then SQLite takes as the error message all text up through the first zero character. ^If the third parameter to sqlite3_result_error() or sqlite3_result_error16() is non-negative then SQLite takes that many bytes (not characters) from the 2nd parameter as the error message. ^The sqlite3_result_error() and sqlite3_result_error16() routines make a private copy of the error message text before they return. Hence, the calling function can deallocate or modify the text after they return without harm. ^The sqlite3_result_error_code() function changes the error code returned by SQLite as a result of an error in a function. ^By default, the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error() or sqlite3_result_error16() resets the error code to SQLITE_ERROR. ^The sqlite3_result_error_toobig() interface causes SQLite to throw an error indicating that a string or BLOB is too long to represent. ^The sqlite3_result_error_nomem() interface causes SQLite to throw an error indicating that a memory allocation failed. ^The sqlite3_result_int() interface sets the return value of the application-defined function to be the 32-bit signed integer value given in the 2nd argument. ^The sqlite3_result_int64() interface sets the return value of the application-defined function to be the 64-bit signed integer value given in the 2nd argument. ^The sqlite3_result_null() interface sets the return value of the application-defined function to be NULL. ^The sqlite3_result_text(), sqlite3_result_text16(), sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces set the return value of the application-defined function to be a text string which is represented as UTF-8, UTF-16 native byte order, UTF-16 little endian, or UTF-16 big endian, respectively. ^The sqlite3_result_text64() interface sets the return value of an application-defined function to be a text string in an encoding specified by the fifth (and last) parameter, which must be one of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]. ^SQLite takes the text result from the application from the 2nd parameter of the sqlite3_result_text* interfaces. ** ^If the 3rd parameter to the sqlite3_result_text* interfaces is negative, then SQLite takes result text from the 2nd parameter through the first zero character. ** ^If the 3rd parameter to the sqlite3_result_text* interfaces is non-negative, then as many bytes (not characters) of the text pointed to by the 2nd parameter are taken as the application-defined function result. If the 3rd parameter is non-negative, then it must be the byte offset into the string where the NUL terminator would appear if the string where NUL terminated. If any NUL characters occur in the string at a byte offset that is less than the value of the 3rd parameter, then the resulting string will contain embedded NULs and the result of expressions operating on strings with embedded NULs is undefined. ** ^If the 4th parameter to the sqlite3_result_text* interfaces or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that function as the destructor on the text or BLOB result when it has finished using that result. ^If the 4th parameter to the sqlite3_result_text* interfaces or to sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite assumes that the text or BLOB result is in constant space and does not copy the content of the parameter nor call a destructor on the content when it has finished using that result. ** ^If the 4th parameter to the sqlite3_result_text* interfaces or sqlite3_result_blob is the special constant SQLITE_TRANSIENT then SQLite makes a copy of the result into space obtained from from [sqlite3_malloc()] before it returns. ^The sqlite3_result_value() interface sets the result of the application-defined function to be a copy the [unprotected sqlite3_value] object specified by the 2nd parameter. ^The sqlite3_result_value() interface makes a copy of the [sqlite3_value] so that the [sqlite3_value] specified in the parameter may change or be deallocated after sqlite3_result_value() returns without harm. ^A [protected sqlite3_value] object may always be used where an [unprotected sqlite3_value] object is required, so either kind of [sqlite3_value] object can be used with this interface. If these routines are called from within the different thread than the one containing the application-defined function that received ** the [sqlite3_context] pointer, the results are undefined. / SQLITE_API void SQLITE_STDCALL sqlite3_result_blob(sqlite3_context, const void, int, void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_blob64(sqlite3_context,const void, sqlite3_uint64,void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_double(sqlite3_context, double); SQLITE_API void SQLITE_STDCALL sqlite3_result_error(sqlite3_context, const char, int); SQLITE_API void SQLITE_STDCALL sqlite3_result_error16(sqlite3_context, const void, int); SQLITE_API void SQLITE_STDCALL sqlite3_result_error_toobig(sqlite3_context); SQLITE_API void SQLITE_STDCALL sqlite3_result_error_nomem(sqlite3_context); SQLITE_API void SQLITE_STDCALL sqlite3_result_error_code(sqlite3_context, int); SQLITE_API void SQLITE_STDCALL sqlite3_result_int(sqlite3_context, int); SQLITE_API void SQLITE_STDCALL sqlite3_result_int64(sqlite3_context, sqlite3_int64); SQLITE_API void SQLITE_STDCALL sqlite3_result_null(sqlite3_context); SQLITE_API void SQLITE_STDCALL sqlite3_result_text(sqlite3_context, const char, int, void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_text64(sqlite3_context, const char,sqlite3_uint64, void()(void), unsigned char encoding); SQLITE_API void SQLITE_STDCALL sqlite3_result_text16(sqlite3_context, const void, int, void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_text16le(sqlite3_context, const void, int,void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_text16be(sqlite3_context, const void, int,void()(void)); SQLITE_API void SQLITE_STDCALL sqlite3_result_value(sqlite3_context, sqlite3_value); SQLITE_API void SQLITE_STDCALL sqlite3_result_zeroblob(sqlite3_context, int n); / CAPI3REF: Define New Collating Sequences METHOD: sqlite3 ^These functions add, remove, or modify a [collation] associated with the [database connection] specified as the first argument. ^The name of the collation is a UTF-8 string for sqlite3_create_collation() and sqlite3_create_collation_v2() and a UTF-16 string in native byte order for sqlite3_create_collation16(). ^Collation names that compare equal according to [sqlite3_strnicmp()] are considered to be the same name. ^(The third argument (eTextRep) must be one of the constants: <ul> <li> [SQLITE_UTF8], <li> [SQLITE_UTF16LE], <li> [SQLITE_UTF16BE], <li> [SQLITE_UTF16], or <li> [SQLITE_UTF16_ALIGNED]. </ul>)^ ^The eTextRep argument determines the encoding of strings passed to the collating function callback, xCallback. ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep force strings to be UTF16 with native byte order. ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin on an even byte address. ^The fourth argument, pArg, is an application data pointer that is passed through as the first argument to the collating function callback. ^The fifth argument, xCallback, is a pointer to the collating function. ^Multiple collating functions can be registered using the same name but with different eTextRep parameters and SQLite will use whichever function requires the least amount of data transformation. ^If the xCallback argument is NULL then the collating function is deleted. ^When all collating functions having the same name are deleted, that collation is no longer usable. ^The collating function callback is invoked with a copy of the pArg application data pointer and with two strings in the encoding specified by the eTextRep argument. The collating function must return an integer that is negative, zero, or positive if the first string is less than, equal to, or greater than the second, respectively. A collating function must always return the same answer given the same inputs. If two or more collating functions are registered to the same collation name (using different eTextRep values) then all must give an equivalent answer when invoked with equivalent strings. The collating function must obey the following properties for all strings A, B, and C: <ol> <li> If A==B then B==A. <li> If A==B and B==C then A==C. <li> If A<B THEN B>A. <li> If A<B and B<C then A<C. </ol> If a collating function fails any of the above constraints and that collating function is registered and used, then the behavior of SQLite is undefined. ^The sqlite3_create_collation_v2() works like sqlite3_create_collation() with the addition that the xDestroy callback is invoked on pArg when the collating function is deleted. ^Collating functions are deleted when they are overridden by later calls to the collation creation functions or when the [database connection] is closed using [sqlite3_close()]. ^The xDestroy callback is <u>not</u> called if the sqlite3_create_collation_v2() function fails. Applications that invoke sqlite3_create_collation_v2() with a non-NULL xDestroy argument should check the return code and dispose of the application data pointer themselves rather than expecting SQLite to deal with it for them. This is different from every other SQLite interface. The inconsistency is unfortunate but cannot be changed without breaking backwards compatibility. See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()]. / SQLITE_API int SQLITE_STDCALL sqlite3_create_collation( sqlite3, const char zName, int eTextRep, void pArg, int(xCompare)(void,int,const void,int,const void) ); SQLITE_API int SQLITE_STDCALL sqlite3_create_collation_v2( sqlite3, const char zName, int eTextRep, void pArg, int(xCompare)(void,int,const void,int,const void), void(xDestroy)(void) ); SQLITE_API int SQLITE_STDCALL sqlite3_create_collation16( sqlite3, const void zName, int eTextRep, void pArg, int(xCompare)(void,int,const void,int,const void) ); /* CAPI3REF: Collation Needed Callbacks METHOD: sqlite3 ^To avoid having to register all collation sequences before a database can be used, a single callback function may be registered with the [database connection] to be invoked whenever an undefined collation sequence is required. ^If the function is registered using the sqlite3_collation_needed() API, then it is passed the names of undefined collation sequences as strings encoded in UTF-8. ^If sqlite3_collation_needed16() is used, the names are passed as UTF-16 in machine native byte order. ^A call to either function replaces the existing collation-needed callback. ^(When the callback is invoked, the first argument passed is a copy of the second argument to sqlite3_collation_needed() or sqlite3_collation_needed16(). The second argument is the database connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE], or [SQLITE_UTF16LE], indicating the most desirable form of the collation sequence function required. The fourth parameter is the name of the required collation sequence.)^ The callback function should register the desired collation using [sqlite3_create_collation()], [sqlite3_create_collation16()], or ** [sqlite3_create_collation_v2()]. / SQLITE_API int SQLITE_STDCALL sqlite3_collation_needed( sqlite3, void, void()(void,sqlite3,int eTextRep,const char) ); SQLITE_API int SQLITE_STDCALL sqlite3_collation_needed16( sqlite3, void, void()(void,sqlite3,int eTextRep,const void) ); #ifdef SQLITE_HAS_CODEC / Specify the key for an encrypted database. This routine should be called right after sqlite3_open(). The code to implement this API is not available in the public release ** of SQLite. / SQLITE_API int SQLITE_STDCALL sqlite3_key( sqlite3 db, /* Database to be rekeyed / const void pKey, int nKey /* The key / ); SQLITE_API int SQLITE_STDCALL sqlite3_key_v2( sqlite3 db, /* Database to be rekeyed / const char zDbName, /* Name of the database / const void pKey, int nKey /* The key / ); / Change the key on an open database. If the current database is not encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the database is decrypted. The code to implement this API is not available in the public release of SQLite. / SQLITE_API int SQLITE_STDCALL sqlite3_rekey( sqlite3 db, /* Database to be rekeyed / const void pKey, int nKey /* The new key / ); SQLITE_API int SQLITE_STDCALL sqlite3_rekey_v2( sqlite3 db, /* Database to be rekeyed / const char zDbName, /* Name of the database / const void pKey, int nKey /* The new key / ); / Specify the activation key for a SEE database. Unless activated, none of the SEE routines will work. / SQLITE_API void SQLITE_STDCALL sqlite3_activate_see( const char zPassPhrase /* Activation phrase / ); #endif #ifdef SQLITE_ENABLE_CEROD / Specify the activation key for a CEROD database. Unless activated, none of the CEROD routines will work. / SQLITE_API void SQLITE_STDCALL sqlite3_activate_cerod( const char zPassPhrase /* Activation phrase / ); #endif / CAPI3REF: Suspend Execution For A Short Time The sqlite3_sleep() function causes the current thread to suspend execution for at least a number of milliseconds specified in its parameter. If the operating system does not support sleep requests with millisecond time resolution, then the time will be rounded up to the nearest second. The number of milliseconds of sleep actually requested from the operating system is returned. ^SQLite implements this interface by calling the xSleep() method of the default [sqlite3_vfs] object. If the xSleep() method of the default VFS is not implemented correctly, or not implemented at all, then the behavior of sqlite3_sleep() may deviate from the description ** in the previous paragraphs. / SQLITE_API int SQLITE_STDCALL sqlite3_sleep(int); / CAPI3REF: Name Of The Folder Holding Temporary Files ^(If this global variable is made to point to a string which is the name of a folder (a.k.a. directory), then all temporary files created by SQLite when using a built-in [sqlite3_vfs \| VFS] will be placed in that directory.)^ ^If this variable is a NULL pointer, then SQLite performs a search for an appropriate temporary file directory. Applications are strongly discouraged from using this global variable. It is required to set a temporary folder on Windows Runtime (WinRT). But for all other platforms, it is highly recommended that applications neither read nor write this variable. This global variable is a relic that exists for backwards compatibility of legacy applications and should be avoided in new projects. It is not safe to read or modify this variable in more than one thread at a time. It is not safe to read or modify this variable if a [database connection] is being used at the same time in a separate thread. It is intended that this variable be set once as part of process initialization and before any SQLite interface routines have been called and that this variable remain unchanged thereafter. ^The [temp_store_directory pragma] may modify this variable and cause it to point to memory obtained from [sqlite3_malloc]. ^Furthermore, the [temp_store_directory pragma] always assumes that any string that this variable points to is held in memory obtained from [sqlite3_malloc] and the pragma may attempt to free that memory using [sqlite3_free]. Hence, if this variable is modified directly, either it should be made NULL or made to point to memory obtained from [sqlite3_malloc] or else the use of the [temp_store_directory pragma] should be avoided. Except when requested by the [temp_store_directory pragma], SQLite does not free the memory that sqlite3_temp_directory points to. If the application wants that memory to be freed, it must do so itself, taking care to only do so after all [database connection] objects have been destroyed. <b>Note to Windows Runtime users:</b> The temporary directory must be set prior to calling [sqlite3_open] or [sqlite3_open_v2]. Otherwise, various features that require the use of temporary files may fail. Here is an example of how to do this using C++ with the Windows Runtime: <blockquote><pre> LPCWSTR zPath = Windows::Storage::ApplicationData::Current->   TemporaryFolder->Path->Data(); char zPathBuf[MAX_PATH + 1]; memset(zPathBuf, 0, sizeof(zPathBuf)); WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),   NULL, NULL); sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf); </pre></blockquote> / SQLITE_API SQLITE_EXTERN char sqlite3_temp_directory; /* CAPI3REF: Name Of The Folder Holding Database Files ^(If this global variable is made to point to a string which is the name of a folder (a.k.a. directory), then all database files specified with a relative pathname and created or accessed by SQLite when using a built-in windows [sqlite3_vfs \| VFS] will be assumed to be relative to that directory.)^ ^If this variable is a NULL pointer, then SQLite assumes that all database files specified with a relative pathname are relative to the current directory for the process. Only the windows VFS makes use of this global variable; it is ignored by the unix VFS. Changing the value of this variable while a database connection is open can result in a corrupt database. It is not safe to read or modify this variable in more than one thread at a time. It is not safe to read or modify this variable if a [database connection] is being used at the same time in a separate thread. It is intended that this variable be set once as part of process initialization and before any SQLite interface routines have been called and that this variable remain unchanged thereafter. ^The [data_store_directory pragma] may modify this variable and cause it to point to memory obtained from [sqlite3_malloc]. ^Furthermore, the [data_store_directory pragma] always assumes that any string that this variable points to is held in memory obtained from [sqlite3_malloc] and the pragma may attempt to free that memory using [sqlite3_free]. Hence, if this variable is modified directly, either it should be made NULL or made to point to memory obtained from [sqlite3_malloc] ** or else the use of the [data_store_directory pragma] should be avoided. / SQLITE_API SQLITE_EXTERN char sqlite3_data_directory; /* CAPI3REF: Test For Auto-Commit Mode KEYWORDS: {autocommit mode} METHOD: sqlite3 ^The sqlite3_get_autocommit() interface returns non-zero or zero if the given database connection is or is not in autocommit mode, respectively. ^Autocommit mode is on by default. ^Autocommit mode is disabled by a [BEGIN] statement. ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK]. If certain kinds of errors occur on a statement within a multi-statement transaction (errors including [SQLITE_FULL], [SQLITE_IOERR], [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the transaction might be rolled back automatically. The only way to find out whether SQLite automatically rolled back the transaction after an error is to use this function. If another thread changes the autocommit status of the database connection while this routine is running, then the return value is undefined. / SQLITE_API int SQLITE_STDCALL sqlite3_get_autocommit(sqlite3); /* CAPI3REF: Find The Database Handle Of A Prepared Statement METHOD: sqlite3_stmt ^The sqlite3_db_handle interface returns the [database connection] handle to which a [prepared statement] belongs. ^The [database connection] returned by sqlite3_db_handle is the same [database connection] that was the first argument to the [sqlite3_prepare_v2()] call (or its variants) that was used to ** create the statement in the first place. / SQLITE_API sqlite3 SQLITE_STDCALL sqlite3_db_handle(sqlite3_stmt); / CAPI3REF: Return The Filename For A Database Connection METHOD: sqlite3 ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename associated with database N of connection D. ^The main database file has the name "main". If there is no attached database N on the database connection D, or if database N is a temporary or in-memory database, then a NULL pointer is returned. ^The filename returned by this function is the output of the xFullPathname method of the [VFS]. ^In other words, the filename will be an absolute pathname, even if the filename used ** to open the database originally was a URI or relative pathname. / SQLITE_API const char SQLITE_STDCALL sqlite3_db_filename(sqlite3 db, const char zDbName); /* CAPI3REF: Determine if a database is read-only METHOD: sqlite3 ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N of connection D is read-only, 0 if it is read/write, or -1 if N is not the name of a database on connection D. / SQLITE_API int SQLITE_STDCALL sqlite3_db_readonly(sqlite3 db, const char zDbName); / CAPI3REF: Find the next prepared statement METHOD: sqlite3 ^This interface returns a pointer to the next [prepared statement] after pStmt associated with the [database connection] pDb. ^If pStmt is NULL then this interface returns a pointer to the first prepared statement associated with the database connection pDb. ^If no prepared statement satisfies the conditions of this routine, it returns NULL. The [database connection] pointer D in a call to [sqlite3_next_stmt(D,S)] must refer to an open database connection and in particular must not be a NULL pointer. / SQLITE_API sqlite3_stmt SQLITE_STDCALL sqlite3_next_stmt(sqlite3 pDb, sqlite3_stmt pStmt); /* CAPI3REF: Commit And Rollback Notification Callbacks METHOD: sqlite3 ^The sqlite3_commit_hook() interface registers a callback function to be invoked whenever a transaction is [COMMIT \| committed]. ^Any callback set by a previous call to sqlite3_commit_hook() for the same database connection is overridden. ^The sqlite3_rollback_hook() interface registers a callback function to be invoked whenever a transaction is [ROLLBACK \| rolled back]. ^Any callback set by a previous call to sqlite3_rollback_hook() for the same database connection is overridden. ^The pArg argument is passed through to the callback. ^If the callback on a commit hook function returns non-zero, then the commit is converted into a rollback. ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions return the P argument from the previous call of the same function on the same [database connection] D, or NULL for the first call for each function on D. The commit and rollback hook callbacks are not reentrant. The callback implementation must not do anything that will modify the database connection that invoked the callback. Any actions to modify the database connection must be deferred until after the completion of the [sqlite3_step()] call that triggered the commit or rollback hook in the first place. Note that running any other SQL statements, including SELECT statements, or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify the database connections for the meaning of "modify" in this paragraph. ^Registering a NULL function disables the callback. ^When the commit hook callback routine returns zero, the [COMMIT] operation is allowed to continue normally. ^If the commit hook returns non-zero, then the [COMMIT] is converted into a [ROLLBACK]. ^The rollback hook is invoked on a rollback that results from a commit hook returning non-zero, just as it would be with any other rollback. ^For the purposes of this API, a transaction is said to have been rolled back if an explicit "ROLLBACK" statement is executed, or an error or constraint causes an implicit rollback to occur. ^The rollback callback is not invoked if a transaction is automatically rolled back because the database connection is closed. ** See also the [sqlite3_update_hook()] interface. / SQLITE_API void SQLITE_STDCALL sqlite3_commit_hook(sqlite3, int()(void), void); SQLITE_API void SQLITE_STDCALL sqlite3_rollback_hook(sqlite3, void()(void ), void); / CAPI3REF: Data Change Notification Callbacks METHOD: sqlite3 ^The sqlite3_update_hook() interface registers a callback function with the [database connection] identified by the first argument to be invoked whenever a row is updated, inserted or deleted in a rowid table. ^Any callback set by a previous call to this function for the same database connection is overridden. ^The second argument is a pointer to the function to invoke when a row is updated, inserted or deleted in a rowid table. ^The first argument to the callback is a copy of the third argument to sqlite3_update_hook(). ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE], or [SQLITE_UPDATE], depending on the operation that caused the callback to be invoked. ^The third and fourth arguments to the callback contain pointers to the database and table name containing the affected row. ^The final callback parameter is the [rowid] of the row. ^In the case of an update, this is the [rowid] after the update takes place. ^(The update hook is not invoked when internal system tables are modified (i.e. sqlite_master and sqlite_sequence).)^ ^The update hook is not invoked when [WITHOUT ROWID] tables are modified. ^In the current implementation, the update hook is not invoked when duplication rows are deleted because of an [ON CONFLICT \| ON CONFLICT REPLACE] clause. ^Nor is the update hook invoked when rows are deleted using the [truncate optimization]. The exceptions defined in this paragraph might change in a future release of SQLite. The update hook implementation must not do anything that will modify the database connection that invoked the update hook. Any actions to modify the database connection must be deferred until after the completion of the [sqlite3_step()] call that triggered the update hook. Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their database connections for the meaning of "modify" in this paragraph. ^The sqlite3_update_hook(D,C,P) function returns the P argument from the previous call on the same [database connection] D, or NULL for the first call on D. See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()] ** interfaces. / SQLITE_API void SQLITE_STDCALL sqlite3_update_hook( sqlite3, void()(void ,int ,char const ,char const ,sqlite3_int64), void ); /* CAPI3REF: Enable Or Disable Shared Pager Cache ^(This routine enables or disables the sharing of the database cache and schema data structures between [database connection \| connections] to the same database. Sharing is enabled if the argument is true and disabled if the argument is false.)^ ^Cache sharing is enabled and disabled for an entire process. This is a change as of SQLite version 3.5.0. In prior versions of SQLite, sharing was enabled or disabled for each thread separately. ^(The cache sharing mode set by this interface effects all subsequent calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()]. Existing database connections continue use the sharing mode that was in effect at the time they were opened.)^ ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled successfully. An [error code] is returned otherwise.)^ ^Shared cache is disabled by default. But this might change in future releases of SQLite. Applications that care about shared cache setting should set it explicitly. Note: This method is disabled on MacOS X 10.7 and iOS version 5.0 and will always return SQLITE_MISUSE. On those systems, shared cache mode should be enabled per-database connection via [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE]. This interface is threadsafe on processors where writing a 32-bit integer is atomic. See Also: [SQLite Shared-Cache Mode] / SQLITE_API int SQLITE_STDCALL sqlite3_enable_shared_cache(int); / CAPI3REF: Attempt To Free Heap Memory ^The sqlite3_release_memory() interface attempts to free N bytes of heap memory by deallocating non-essential memory allocations held by the database library. Memory used to cache database pages to improve performance is an example of non-essential memory. ^sqlite3_release_memory() returns the number of bytes actually freed, which might be more or less than the amount requested. ^The sqlite3_release_memory() routine is a no-op returning zero if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT]. See also: [sqlite3_db_release_memory()] / SQLITE_API int SQLITE_STDCALL sqlite3_release_memory(int); / CAPI3REF: Free Memory Used By A Database Connection METHOD: sqlite3 ^The sqlite3_db_release_memory(D) interface attempts to free as much heap memory as possible from database connection D. Unlike the [sqlite3_release_memory()] interface, this interface is in effect even when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is omitted. See also: [sqlite3_release_memory()] / SQLITE_API int SQLITE_STDCALL sqlite3_db_release_memory(sqlite3); /* CAPI3REF: Impose A Limit On Heap Size ^The sqlite3_soft_heap_limit64() interface sets and/or queries the soft limit on the amount of heap memory that may be allocated by SQLite. ^SQLite strives to keep heap memory utilization below the soft heap limit by reducing the number of pages held in the page cache as heap memory usages approaches the limit. ^The soft heap limit is "soft" because even though SQLite strives to stay below the limit, it will exceed the limit rather than generate an [SQLITE_NOMEM] error. In other words, the soft heap limit is advisory only. ^The return value from sqlite3_soft_heap_limit64() is the size of the soft heap limit prior to the call, or negative in the case of an error. ^If the argument N is negative then no change is made to the soft heap limit. Hence, the current size of the soft heap limit can be determined by invoking sqlite3_soft_heap_limit64() with a negative argument. ^If the argument N is zero then the soft heap limit is disabled. ^(The soft heap limit is not enforced in the current implementation if one or more of following conditions are true: <ul> <li> The soft heap limit is set to zero. <li> Memory accounting is disabled using a combination of the [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and the [SQLITE_DEFAULT_MEMSTATUS] compile-time option. <li> An alternative page cache implementation is specified using [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...). <li> The page cache allocates from its own memory pool supplied by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than from the heap. </ul>)^ Beginning with SQLite version 3.7.3, the soft heap limit is enforced regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is enforced on every memory allocation. Without [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced when memory is allocated by the page cache. Testing suggests that because the page cache is the predominate memory user in SQLite, most applications will achieve adequate soft heap limit enforcement without the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT]. The circumstances under which SQLite will enforce the soft heap limit may changes in future releases of SQLite. / SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_soft_heap_limit64(sqlite3_int64 N); / CAPI3REF: Deprecated Soft Heap Limit Interface DEPRECATED This is a deprecated version of the [sqlite3_soft_heap_limit64()] interface. This routine is provided for historical compatibility only. All new applications should use the ** [sqlite3_soft_heap_limit64()] interface rather than this one. / SQLITE_API SQLITE_DEPRECATED void SQLITE_STDCALL sqlite3_soft_heap_limit(int N); / CAPI3REF: Extract Metadata About A Column Of A Table METHOD: sqlite3 ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns information about column C of table T in database D on [database connection] X.)^ ^The sqlite3_table_column_metadata() interface returns SQLITE_OK and fills in the non-NULL pointers in the final five arguments with appropriate values if the specified column exists. ^The sqlite3_table_column_metadata() interface returns SQLITE_ERROR and if the specified column does not exist. ^If the column-name parameter to sqlite3_table_column_metadata() is a NULL pointer, then this routine simply checks for the existance of the table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it does not. ^The column is identified by the second, third and fourth parameters to this function. ^(The second parameter is either the name of the database (i.e. "main", "temp", or an attached database) containing the specified table or NULL.)^ ^If it is NULL, then all attached databases are searched for the table using the same algorithm used by the database engine to resolve unqualified table references. ^The third and fourth parameters to this function are the table and column name of the desired column, respectively. ^Metadata is returned by writing to the memory locations passed as the 5th and subsequent parameters to this function. ^Any of these arguments may be NULL, in which case the corresponding element of metadata is omitted. ^(<blockquote> <table border="1"> <tr><th> Parameter <th> Output<br>Type <th> Description <tr><td> 5th <td> const char* <td> Data type ** <tr><td> 6th <td> const char* <td> Name of default collation sequence <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT] </table> </blockquote>)^ ^The memory pointed to by the character pointers returned for the declaration type and collation sequence is valid until the next call to any SQLite API function. ^If the specified table is actually a view, an [error code] is returned. ^If the specified column is "rowid", "oid" or "_rowid_" and the table is not a [WITHOUT ROWID] table and an [INTEGER PRIMARY KEY] column has been explicitly declared, then the output parameters are set for the explicitly declared column. ^(If there is no [INTEGER PRIMARY KEY] column, then the outputs for the [rowid] are set as follows: <pre> data type: "INTEGER" collation sequence: "BINARY" not null: 0 primary key: 1 auto increment: 0 </pre>)^ ^This function causes all database schemas to be read from disk and parsed, if that has not already been done, and returns an error if any errors are encountered while loading the schema. / SQLITE_API int SQLITE_STDCALL sqlite3_table_column_metadata( sqlite3 db, /* Connection handle / const char zDbName, /* Database name or NULL / const char zTableName, /* Table name / const char zColumnName, /* Column name / char const pzDataType, / OUTPUT: Declared data type / char const pzCollSeq, / OUTPUT: Collation sequence name / int pNotNull, /* OUTPUT: True if NOT NULL constraint exists / int pPrimaryKey, /* OUTPUT: True if column part of PK / int pAutoinc /* OUTPUT: True if column is auto-increment / ); / CAPI3REF: Load An Extension METHOD: sqlite3 ^This interface loads an SQLite extension library from the named file. ^The sqlite3_load_extension() interface attempts to load an [SQLite extension] library contained in the file zFile. If the file cannot be loaded directly, attempts are made to load with various operating-system specific extensions added. So for example, if "samplelib" cannot be loaded, then names like "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might be tried also. ^The entry point is zProc. ^(zProc may be 0, in which case SQLite will try to come up with an entry point name on its own. It first tries "sqlite3_extension_init". If that does not work, it constructs a name "sqlite3_X_init" where the X is consists of the lower-case equivalent of all ASCII alphabetic characters in the filename from the last "/" to the first following "." and omitting any initial "lib".)^ ^The sqlite3_load_extension() interface returns [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong. ^If an error occurs and pzErrMsg is not 0, then the [sqlite3_load_extension()] interface shall attempt to ** fill pzErrMsg with error message text stored in memory * obtained from [sqlite3_malloc()]. The calling function should free this memory by calling [sqlite3_free()]. ^Extension loading must be enabled using [sqlite3_enable_load_extension()] prior to calling this API, otherwise an error will be returned. ** See also the [load_extension() SQL function]. / SQLITE_API int SQLITE_STDCALL sqlite3_load_extension( sqlite3 db, /* Load the extension into this database connection / const char zFile, /* Name of the shared library containing extension / const char zProc, /* Entry point. Derived from zFile if 0 / char pzErrMsg / Put error message here if not 0 / ); / CAPI3REF: Enable Or Disable Extension Loading METHOD: sqlite3 ^So as not to open security holes in older applications that are unprepared to deal with [extension loading], and as a means of disabling [extension loading] while evaluating user-entered SQL, the following API is provided to turn the [sqlite3_load_extension()] mechanism on and off. ^Extension loading is off by default. ^Call the sqlite3_enable_load_extension() routine with onoff==1 to turn extension loading on and call it with onoff==0 to turn it back off again. / SQLITE_API int SQLITE_STDCALL sqlite3_enable_load_extension(sqlite3 db, int onoff); /* CAPI3REF: Automatically Load Statically Linked Extensions ^This interface causes the xEntryPoint() function to be invoked for each new [database connection] that is created. The idea here is that xEntryPoint() is the entry point for a statically linked [SQLite extension] that is to be automatically loaded into all new database connections. ^(Even though the function prototype shows that xEntryPoint() takes no arguments and returns void, SQLite invokes xEntryPoint() with three arguments and expects and integer result as if the signature of the entry point where as follows: <blockquote><pre>   int xEntryPoint( **   sqlite3 db, *   const char pzErrMsg,   const struct sqlite3_api_routines pThunk *   ); </pre></blockquote>)^ ** If the xEntryPoint routine encounters an error, it should make pzErrMsg * point to an appropriate error message (obtained from [sqlite3_mprintf()]) ** and return an appropriate [error code]. ^SQLite ensures that pzErrMsg * is NULL before calling the xEntryPoint(). ^SQLite will invoke ** [sqlite3_free()] on pzErrMsg after xEntryPoint() returns. ^If any * xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()], or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail. ^Calling sqlite3_auto_extension(X) with an entry point X that is already on the list of automatic extensions is a harmless no-op. ^No entry point will be called more than once for each database connection that is opened. See also: [sqlite3_reset_auto_extension()] and [sqlite3_cancel_auto_extension()] / SQLITE_API int SQLITE_STDCALL sqlite3_auto_extension(void (xEntryPoint)(void)); /* CAPI3REF: Cancel Automatic Extension Loading ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the initialization routine X that was registered using a prior call to [sqlite3_auto_extension(X)]. ^The [sqlite3_cancel_auto_extension(X)] routine returns 1 if initialization routine X was successfully unregistered and it returns 0 if X was not on the list of initialization routines. / SQLITE_API int SQLITE_STDCALL sqlite3_cancel_auto_extension(void (xEntryPoint)(void)); /* CAPI3REF: Reset Automatic Extension Loading ^This interface disables all automatic extensions previously registered using [sqlite3_auto_extension()]. / SQLITE_API void SQLITE_STDCALL sqlite3_reset_auto_extension(void); / The interface to the virtual-table mechanism is currently considered to be experimental. The interface might change in incompatible ways. If this is a problem for you, do not use the interface at this time. When the virtual-table mechanism stabilizes, we will declare the interface fixed, support it indefinitely, and remove this comment. / / ** Structures used by the virtual table interface / typedef struct sqlite3_vtab sqlite3_vtab; typedef struct sqlite3_index_info sqlite3_index_info; typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor; typedef struct sqlite3_module sqlite3_module; / CAPI3REF: Virtual Table Object KEYWORDS: sqlite3_module {virtual table module} This structure, sometimes called a "virtual table module", defines the implementation of a [virtual tables]. This structure consists mostly of methods for the module. ^A virtual table module is created by filling in a persistent instance of this structure and passing a pointer to that instance to [sqlite3_create_module()] or [sqlite3_create_module_v2()]. ^The registration remains valid until it is replaced by a different module or until the [database connection] closes. The content of this structure must not change while it is registered with any database connection. / struct sqlite3_module { int iVersion; int (xCreate)(sqlite3, void pAux, int argc, const char constargv, sqlite3_vtab ppVTab, char); int (xConnect)(sqlite3, void pAux, int argc, const char constargv, sqlite3_vtab ppVTab, char); int (xBestIndex)(sqlite3_vtab pVTab, sqlite3_index_info); int (xDisconnect)(sqlite3_vtab pVTab); int (xDestroy)(sqlite3_vtab pVTab); int (xOpen)(sqlite3_vtab pVTab, sqlite3_vtab_cursor *ppCursor); int (xClose)(sqlite3_vtab_cursor); int (xFilter)(sqlite3_vtab_cursor, int idxNum, const char idxStr, int argc, sqlite3_value *argv); int (xNext)(sqlite3_vtab_cursor); int (xEof)(sqlite3_vtab_cursor); int (xColumn)(sqlite3_vtab_cursor, sqlite3_context, int); int (xRowid)(sqlite3_vtab_cursor, sqlite3_int64 pRowid); int (xUpdate)(sqlite3_vtab , int, sqlite3_value , sqlite3_int64 ); int (xBegin)(sqlite3_vtab pVTab); int (xSync)(sqlite3_vtab pVTab); int (xCommit)(sqlite3_vtab pVTab); int (xRollback)(sqlite3_vtab pVTab); int (xFindFunction)(sqlite3_vtab pVtab, int nArg, const char zName, void (pxFunc)(sqlite3_context,int,sqlite3_value), void ppArg); int (xRename)(sqlite3_vtab pVtab, const char zNew); / The methods above are in version 1 of the sqlite_module object. Those ** below are for version 2 and greater. / int (xSavepoint)(sqlite3_vtab pVTab, int); int (xRelease)(sqlite3_vtab pVTab, int); int (xRollbackTo)(sqlite3_vtab pVTab, int); }; / CAPI3REF: Virtual Table Indexing Information KEYWORDS: sqlite3_index_info The sqlite3_index_info structure and its substructures is used as part of the [virtual table] interface to pass information into and receive the reply from the [xBestIndex] method of a [virtual table module]. The fields under Inputs are the inputs to xBestIndex and are read-only. xBestIndex inserts its results into the Outputs fields. ^(The aConstraint[] array records WHERE clause constraints of the form: <blockquote>column OP expr</blockquote> where OP is =, <, <=, >, or >=.)^ ^(The particular operator is stored in aConstraint[].op using one of the [SQLITE_INDEX_CONSTRAINT_EQ \| SQLITE_INDEX_CONSTRAINT_ values].)^ ^(The index of the column is stored in aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the expr on the right-hand side can be evaluated (and thus the constraint is usable) and false if it cannot.)^ ^The optimizer automatically inverts terms of the form "expr OP column" and makes other simplifications to the WHERE clause in an attempt to get as many WHERE clause terms into the form shown above as possible. ^The aConstraint[] array only reports WHERE clause terms that are relevant to the particular virtual table being queried. ^Information about the ORDER BY clause is stored in aOrderBy[]. ^Each term of aOrderBy records a column of the ORDER BY clause. The [xBestIndex] method must fill aConstraintUsage[] with information about what parameters to pass to xFilter. ^If argvIndex>0 then the right-hand side of the corresponding aConstraint[] is evaluated and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit is true, then the constraint is assumed to be fully handled by the virtual table and is not checked again by SQLite.)^ ^The idxNum and idxPtr values are recorded and passed into the [xFilter] method. ^[sqlite3_free()] is used to free idxPtr if and only if needToFreeIdxPtr is true. ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in the correct order to satisfy the ORDER BY clause so that no separate sorting step is required. ^The estimatedCost value is an estimate of the cost of a particular strategy. A cost of N indicates that the cost of the strategy is similar to a linear scan of an SQLite table with N rows. A cost of log(N) indicates that the expense of the operation is similar to that of a binary search on a unique indexed field of an SQLite table with N rows. ^The estimatedRows value is an estimate of the number of rows that will be returned by the strategy. IMPORTANT: The estimatedRows field was added to the sqlite3_index_info structure for SQLite version 3.8.2. If a virtual table extension is used with an SQLite version earlier than 3.8.2, the results of attempting to read or write the estimatedRows field are undefined (but are likely to included crashing the application). The estimatedRows field should therefore only be used if [sqlite3_libversion_number()] returns a ** value greater than or equal to 3008002. / struct sqlite3_index_info { / Inputs / int nConstraint; / Number of entries in aConstraint / struct sqlite3_index_constraint { int iColumn; / Column on left-hand side of constraint / unsigned char op; / Constraint operator / unsigned char usable; / True if this constraint is usable / int iTermOffset; / Used internally - xBestIndex should ignore / } aConstraint; /* Table of WHERE clause constraints / int nOrderBy; / Number of terms in the ORDER BY clause / struct sqlite3_index_orderby { int iColumn; / Column number / unsigned char desc; / True for DESC. False for ASC. / } aOrderBy; /* The ORDER BY clause / / Outputs / struct sqlite3_index_constraint_usage { int argvIndex; / if >0, constraint is part of argv to xFilter / unsigned char omit; / Do not code a test for this constraint / } aConstraintUsage; int idxNum; /* Number used to identify the index / char idxStr; /* String, possibly obtained from sqlite3_malloc / int needToFreeIdxStr; / Free idxStr using sqlite3_free() if true / int orderByConsumed; / True if output is already ordered / double estimatedCost; / Estimated cost of using this index / / Fields below are only available in SQLite 3.8.2 and later / sqlite3_int64 estimatedRows; / Estimated number of rows returned / }; / CAPI3REF: Virtual Table Constraint Operator Codes These macros defined the allowed values for the [sqlite3_index_info].aConstraint[].op field. Each value represents an operator that is part of a constraint term in the wHERE clause of a query that uses a [virtual table]. / #define SQLITE_INDEX_CONSTRAINT_EQ 2 #define SQLITE_INDEX_CONSTRAINT_GT 4 #define SQLITE_INDEX_CONSTRAINT_LE 8 #define SQLITE_INDEX_CONSTRAINT_LT 16 #define SQLITE_INDEX_CONSTRAINT_GE 32 #define SQLITE_INDEX_CONSTRAINT_MATCH 64 / CAPI3REF: Register A Virtual Table Implementation METHOD: sqlite3 ^These routines are used to register a new [virtual table module] name. ^Module names must be registered before creating a new [virtual table] using the module and before using a preexisting [virtual table] for the module. ^The module name is registered on the [database connection] specified by the first parameter. ^The name of the module is given by the second parameter. ^The third parameter is a pointer to the implementation of the [virtual table module]. ^The fourth parameter is an arbitrary client data pointer that is passed through into the [xCreate] and [xConnect] methods of the virtual table module when a new virtual table is be being created or reinitialized. ^The sqlite3_create_module_v2() interface has a fifth parameter which is a pointer to a destructor for the pClientData. ^SQLite will invoke the destructor function (if it is not NULL) when SQLite no longer needs the pClientData pointer. ^The destructor will also be invoked if the call to sqlite3_create_module_v2() fails. ^The sqlite3_create_module() interface is equivalent to sqlite3_create_module_v2() with a NULL destructor. / SQLITE_API int SQLITE_STDCALL sqlite3_create_module( sqlite3 db, /* SQLite connection to register module with / const char zName, /* Name of the module / const sqlite3_module p, /* Methods for the module / void pClientData /* Client data for xCreate/xConnect / ); SQLITE_API int SQLITE_STDCALL sqlite3_create_module_v2( sqlite3 db, /* SQLite connection to register module with / const char zName, /* Name of the module / const sqlite3_module p, /* Methods for the module / void pClientData, /* Client data for xCreate/xConnect / void(xDestroy)(void) / Module destructor function / ); / CAPI3REF: Virtual Table Instance Object KEYWORDS: sqlite3_vtab Every [virtual table module] implementation uses a subclass of this object to describe a particular instance of the [virtual table]. Each subclass will be tailored to the specific needs of the module implementation. The purpose of this superclass is to define certain fields that are common to all module implementations. ^Virtual tables methods can set an error message by assigning a string obtained from [sqlite3_mprintf()] to zErrMsg. The method should take care that any prior string is freed by a call to [sqlite3_free()] prior to assigning a new string to zErrMsg. ^After the error message is delivered up to the client application, the string will be automatically freed by sqlite3_free() and the zErrMsg field will be zeroed. / struct sqlite3_vtab { const sqlite3_module pModule; /* The module for this virtual table / int nRef; / Number of open cursors / char zErrMsg; /* Error message from sqlite3_mprintf() / / Virtual table implementations will typically add additional fields / }; / CAPI3REF: Virtual Table Cursor Object KEYWORDS: sqlite3_vtab_cursor {virtual table cursor} Every [virtual table module] implementation uses a subclass of the following structure to describe cursors that point into the [virtual table] and are used to loop through the virtual table. Cursors are created using the [sqlite3_module.xOpen \| xOpen] method of the module and are destroyed by the [sqlite3_module.xClose \| xClose] method. Cursors are used by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods of the module. Each module implementation will define the content of a cursor structure to suit its own needs. This superclass exists in order to define fields of the cursor that ** are common to all implementations. / struct sqlite3_vtab_cursor { sqlite3_vtab pVtab; /* Virtual table of this cursor / / Virtual table implementations will typically add additional fields / }; / CAPI3REF: Declare The Schema Of A Virtual Table ^The [xCreate] and [xConnect] methods of a [virtual table module] call this interface to declare the format (the names and datatypes of the columns) of the virtual tables they implement. / SQLITE_API int SQLITE_STDCALL sqlite3_declare_vtab(sqlite3, const char zSQL); / CAPI3REF: Overload A Function For A Virtual Table METHOD: sqlite3 ^(Virtual tables can provide alternative implementations of functions using the [xFindFunction] method of the [virtual table module]. But global versions of those functions must exist in order to be overloaded.)^ ^(This API makes sure a global version of a function with a particular name and number of parameters exists. If no such function exists before this API is called, a new function is created.)^ ^The implementation of the new function always causes an exception to be thrown. So the new function is not good for anything by itself. Its only purpose is to be a placeholder function that can be overloaded ** by a [virtual table]. / SQLITE_API int SQLITE_STDCALL sqlite3_overload_function(sqlite3, const char zFuncName, int nArg); / The interface to the virtual-table mechanism defined above (back up to a comment remarkably similar to this one) is currently considered to be experimental. The interface might change in incompatible ways. If this is a problem for you, do not use the interface at this time. When the virtual-table mechanism stabilizes, we will declare the ** interface fixed, support it indefinitely, and remove this comment. / / CAPI3REF: A Handle To An Open BLOB KEYWORDS: {BLOB handle} {BLOB handles} An instance of this object represents an open BLOB on which [sqlite3_blob_open \| incremental BLOB I/O] can be performed. ^Objects of this type are created by [sqlite3_blob_open()] and destroyed by [sqlite3_blob_close()]. ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces can be used to read or write small subsections of the BLOB. ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes. / typedef struct sqlite3_blob sqlite3_blob; / CAPI3REF: Open A BLOB For Incremental I/O METHOD: sqlite3 CONSTRUCTOR: sqlite3_blob ^(This interfaces opens a [BLOB handle \| handle] to the BLOB located in row iRow, column zColumn, table zTable in database zDb; in other words, the same BLOB that would be selected by: <pre> SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow; </pre>)^ ^(Parameter zDb is not the filename that contains the database, but rather the symbolic name of the database. For attached databases, this is the name that appears after the AS keyword in the [ATTACH] statement. For the main database file, the database name is "main". For TEMP tables, the database name is "temp".)^ ^If the flags parameter is non-zero, then the BLOB is opened for read and write access. ^If the flags parameter is zero, the BLOB is opened for read-only access. ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is stored in ppBlob. Otherwise an [error code] is returned and, unless the error * code is SQLITE_MISUSE, ppBlob is set to NULL.)^ ^This means that, provided * the API is not misused, it is always safe to call [sqlite3_blob_close()] ** on ppBlob after this function it returns. * This function fails with SQLITE_ERROR if any of the following are true: <ul> <li> ^(Database zDb does not exist)^, <li> ^(Table zTable does not exist within database zDb)^, <li> ^(Table zTable is a WITHOUT ROWID table)^, <li> ^(Column zColumn does not exist)^, <li> ^(Row iRow is not present in the table)^, <li> ^(The specified column of row iRow contains a value that is not a TEXT or BLOB value)^, <li> ^(Column zColumn is part of an index, PRIMARY KEY or UNIQUE constraint and the blob is being opened for read/write access)^, <li> ^([foreign key constraints \| Foreign key constraints] are enabled, column zColumn is part of a [child key] definition and the blob is being opened for read/write access)^. </ul> ^Unless it returns SQLITE_MISUSE, this function sets the [database connection] error code and message accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. ^(If the row that a BLOB handle points to is modified by an [UPDATE], [DELETE], or by [ON CONFLICT] side-effects then the BLOB handle is marked as "expired". This is true if any column of the row is changed, even a column other than the one the BLOB handle is open on.)^ ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for an expired BLOB handle fail with a return code of [SQLITE_ABORT]. ^(Changes written into a BLOB prior to the BLOB expiring are not rolled back by the expiration of the BLOB. Such changes will eventually commit if the transaction continues to completion.)^ ^Use the [sqlite3_blob_bytes()] interface to determine the size of the opened blob. ^The size of a blob may not be changed by this interface. Use the [UPDATE] SQL command to change the size of a blob. ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces and the built-in [zeroblob] SQL function may be used to create a zero-filled blob to read or write using the incremental-blob interface. To avoid a resource leak, every open [BLOB handle] should eventually ** be released by a call to [sqlite3_blob_close()]. / SQLITE_API int SQLITE_STDCALL sqlite3_blob_open( sqlite3, const char zDb, const char zTable, const char zColumn, sqlite3_int64 iRow, int flags, sqlite3_blob ppBlob ); / CAPI3REF: Move a BLOB Handle to a New Row METHOD: sqlite3_blob ^This function is used to move an existing blob handle so that it points to a different row of the same database table. ^The new row is identified by the rowid value passed as the second argument. Only the row can be changed. ^The database, table and column on which the blob handle is open remain the same. Moving an existing blob handle to a new row can be faster than closing the existing handle and opening a new one. ^(The new row must meet the same criteria as for [sqlite3_blob_open()] - it must exist and there must be either a blob or text value stored in the nominated column.)^ ^If the new row is not present in the table, or if it does not contain a blob or text value, or if another error occurs, an SQLite error code is returned and the blob handle is considered aborted. ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or [sqlite3_blob_reopen()] on an aborted blob handle immediately return SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle always returns zero. ** ^This function sets the database handle error code and message. / SQLITE_API SQLITE_EXPERIMENTAL int SQLITE_STDCALL sqlite3_blob_reopen(sqlite3_blob , sqlite3_int64); /* CAPI3REF: Close A BLOB Handle DESTRUCTOR: sqlite3_blob ^This function closes an open [BLOB handle]. ^(The BLOB handle is closed unconditionally. Even if this routine returns an error code, the handle is still closed.)^ ^If the blob handle being closed was opened for read-write access, and if the database is in auto-commit mode and there are no other open read-write blob handles or active write statements, the current transaction is committed. ^If an error occurs while committing the transaction, an error code is returned and the transaction rolled back. Calling this function with an argument that is not a NULL pointer or an open blob handle results in undefined behaviour. ^Calling this routine with a null pointer (such as would be returned by a failed call to [sqlite3_blob_open()]) is a harmless no-op. ^Otherwise, if this function is passed a valid open blob handle, the values returned by the ** sqlite3_errcode() and sqlite3_errmsg() functions are set before returning. / SQLITE_API int SQLITE_STDCALL sqlite3_blob_close(sqlite3_blob ); /* CAPI3REF: Return The Size Of An Open BLOB METHOD: sqlite3_blob ^Returns the size in bytes of the BLOB accessible via the successfully opened [BLOB handle] in its only argument. ^The incremental blob I/O routines can only read or overwriting existing blob content; they cannot change the size of a blob. This routine only works on a [BLOB handle] which has been created by a prior successful call to [sqlite3_blob_open()] and which has not been closed by [sqlite3_blob_close()]. Passing any other pointer in to this routine results in undefined and probably undesirable behavior. / SQLITE_API int SQLITE_STDCALL sqlite3_blob_bytes(sqlite3_blob ); /* CAPI3REF: Read Data From A BLOB Incrementally METHOD: sqlite3_blob ^(This function is used to read data from an open [BLOB handle] into a caller-supplied buffer. N bytes of data are copied into buffer Z from the open BLOB, starting at offset iOffset.)^ ^If offset iOffset is less than N bytes from the end of the BLOB, [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is less than zero, [SQLITE_ERROR] is returned and no data is read. ^The size of the blob (and hence the maximum value of N+iOffset) can be determined using the [sqlite3_blob_bytes()] interface. ^An attempt to read from an expired [BLOB handle] fails with an error code of [SQLITE_ABORT]. ^(On success, sqlite3_blob_read() returns SQLITE_OK. Otherwise, an [error code] or an [extended error code] is returned.)^ This routine only works on a [BLOB handle] which has been created by a prior successful call to [sqlite3_blob_open()] and which has not been closed by [sqlite3_blob_close()]. Passing any other pointer in to this routine results in undefined and probably undesirable behavior. ** See also: [sqlite3_blob_write()]. / SQLITE_API int SQLITE_STDCALL sqlite3_blob_read(sqlite3_blob , void Z, int N, int iOffset); / CAPI3REF: Write Data Into A BLOB Incrementally METHOD: sqlite3_blob ^(This function is used to write data into an open [BLOB handle] from a caller-supplied buffer. N bytes of data are copied from the buffer Z into the open BLOB, starting at offset iOffset.)^ ^(On success, sqlite3_blob_write() returns SQLITE_OK. Otherwise, an [error code] or an [extended error code] is returned.)^ ^Unless SQLITE_MISUSE is returned, this function sets the [database connection] error code and message accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. ^If the [BLOB handle] passed as the first argument was not opened for writing (the flags parameter to [sqlite3_blob_open()] was zero), this function returns [SQLITE_READONLY]. This function may only modify the contents of the BLOB; it is not possible to increase the size of a BLOB using this API. ^If offset iOffset is less than N bytes from the end of the BLOB, [SQLITE_ERROR] is returned and no data is written. The size of the BLOB (and hence the maximum value of N+iOffset) can be determined using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less than zero [SQLITE_ERROR] is returned and no data is written. ^An attempt to write to an expired [BLOB handle] fails with an error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred before the [BLOB handle] expired are not rolled back by the expiration of the handle, though of course those changes might have been overwritten by the statement that expired the BLOB handle or by other independent statements. This routine only works on a [BLOB handle] which has been created by a prior successful call to [sqlite3_blob_open()] and which has not been closed by [sqlite3_blob_close()]. Passing any other pointer in to this routine results in undefined and probably undesirable behavior. See also: [sqlite3_blob_read()]. / SQLITE_API int SQLITE_STDCALL sqlite3_blob_write(sqlite3_blob , const void z, int n, int iOffset); / CAPI3REF: Virtual File System Objects A virtual filesystem (VFS) is an [sqlite3_vfs] object that SQLite uses to interact with the underlying operating system. Most SQLite builds come with a single default VFS that is appropriate for the host computer. New VFSes can be registered and existing VFSes can be unregistered. The following interfaces are provided. ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name. ^Names are case sensitive. ^Names are zero-terminated UTF-8 strings. ^If there is no match, a NULL pointer is returned. ^If zVfsName is NULL then the default VFS is returned. ^New VFSes are registered with sqlite3_vfs_register(). ^Each new VFS becomes the default VFS if the makeDflt flag is set. ^The same VFS can be registered multiple times without injury. ^To make an existing VFS into the default VFS, register it again with the makeDflt flag set. If two different VFSes with the same name are registered, the behavior is undefined. If a VFS is registered with a name that is NULL or an empty string, then the behavior is undefined. ^Unregister a VFS with the sqlite3_vfs_unregister() interface. ^(If the default VFS is unregistered, another VFS is chosen as ** the default. The choice for the new VFS is arbitrary.)^ / SQLITE_API sqlite3_vfs SQLITE_STDCALL sqlite3_vfs_find(const char zVfsName); SQLITE_API int SQLITE_STDCALL sqlite3_vfs_register(sqlite3_vfs, int makeDflt); SQLITE_API int SQLITE_STDCALL sqlite3_vfs_unregister(sqlite3_vfs); / CAPI3REF: Mutexes The SQLite core uses these routines for thread synchronization. Though they are intended for internal use by SQLite, code that links against SQLite is permitted to use any of these routines. The SQLite source code contains multiple implementations of these mutex routines. An appropriate implementation is selected automatically at compile-time. The following implementations are available in the SQLite core: <ul> <li> SQLITE_MUTEX_PTHREADS <li> SQLITE_MUTEX_W32 <li> SQLITE_MUTEX_NOOP </ul> The SQLITE_MUTEX_NOOP implementation is a set of routines that does no real locking and is appropriate for use in a single-threaded application. The SQLITE_MUTEX_PTHREADS and SQLITE_MUTEX_W32 implementations are appropriate for use on Unix and Windows. If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex implementation is included with the library. In this case the application must supply a custom mutex implementation using the [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function before calling sqlite3_initialize() or any other public sqlite3_ function that calls sqlite3_initialize(). ^The sqlite3_mutex_alloc() routine allocates a new mutex and returns a pointer to it. ^The sqlite3_mutex_alloc() routine returns NULL if it is unable to allocate the requested mutex. The argument to sqlite3_mutex_alloc() must one of these integer constants: <ul> <li> SQLITE_MUTEX_FAST <li> SQLITE_MUTEX_RECURSIVE <li> SQLITE_MUTEX_STATIC_MASTER <li> SQLITE_MUTEX_STATIC_MEM <li> SQLITE_MUTEX_STATIC_OPEN <li> SQLITE_MUTEX_STATIC_PRNG <li> SQLITE_MUTEX_STATIC_LRU <li> SQLITE_MUTEX_STATIC_PMEM <li> SQLITE_MUTEX_STATIC_APP1 <li> SQLITE_MUTEX_STATIC_APP2 <li> SQLITE_MUTEX_STATIC_APP3 </ul> ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) cause sqlite3_mutex_alloc() to create a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE is used but not necessarily so when SQLITE_MUTEX_FAST is used. The mutex implementation does not need to make a distinction between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does not want to. SQLite will only request a recursive mutex in cases where it really needs one. If a faster non-recursive mutex implementation is available on the host platform, the mutex subsystem might return such a mutex in response to SQLITE_MUTEX_FAST. ^The other allowed parameters to sqlite3_mutex_alloc() (anything other than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return a pointer to a static preexisting mutex. ^Nine static mutexes are used by the current version of SQLite. Future versions of SQLite may add additional static mutexes. Static mutexes are for internal use by SQLite only. Applications that use SQLite mutexes should use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or SQLITE_MUTEX_RECURSIVE. ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc() returns a different mutex on every call. ^For the static mutex types, the same mutex is returned on every call that has the same type number. ^The sqlite3_mutex_free() routine deallocates a previously allocated dynamic mutex. Attempting to deallocate a static mutex results in undefined behavior. ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt to enter a mutex. ^If another thread is already within the mutex, sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK] upon successful entry. ^(Mutexes created using SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread. In such cases, the mutex must be exited an equal number of times before another thread can enter.)^ If the same thread tries to enter any mutex other than an SQLITE_MUTEX_RECURSIVE more than once, the behavior is undefined. ^(Some systems (for example, Windows 95) do not support the operation implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try() will always return SQLITE_BUSY. The SQLite core only ever uses sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^ ^The sqlite3_mutex_leave() routine exits a mutex that was previously entered by the same thread. The behavior is undefined if the mutex is not currently entered by the calling thread or is not currently allocated. ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or sqlite3_mutex_leave() is a NULL pointer, then all three routines behave as no-ops. ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()]. / SQLITE_API sqlite3_mutex SQLITE_STDCALL sqlite3_mutex_alloc(int); SQLITE_API void SQLITE_STDCALL sqlite3_mutex_free(sqlite3_mutex); SQLITE_API void SQLITE_STDCALL sqlite3_mutex_enter(sqlite3_mutex); SQLITE_API int SQLITE_STDCALL sqlite3_mutex_try(sqlite3_mutex); SQLITE_API void SQLITE_STDCALL sqlite3_mutex_leave(sqlite3_mutex); /* CAPI3REF: Mutex Methods Object An instance of this structure defines the low-level routines used to allocate and use mutexes. Usually, the default mutex implementations provided by SQLite are sufficient, however the application has the option of substituting a custom implementation for specialized deployments or systems for which SQLite does not provide a suitable implementation. In this case, the application creates and populates an instance of this structure to pass to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option. Additionally, an instance of this structure can be used as an output variable when querying the system for the current mutex implementation, using the [SQLITE_CONFIG_GETMUTEX] option. ^The xMutexInit method defined by this structure is invoked as part of system initialization by the sqlite3_initialize() function. ^The xMutexInit routine is called by SQLite exactly once for each effective call to [sqlite3_initialize()]. ^The xMutexEnd method defined by this structure is invoked as part of system shutdown by the sqlite3_shutdown() function. The implementation of this method is expected to release all outstanding resources obtained by the mutex methods implementation, especially those obtained by the xMutexInit method. ^The xMutexEnd() interface is invoked exactly once for each call to [sqlite3_shutdown()]. ^(The remaining seven methods defined by this structure (xMutexAlloc, xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and xMutexNotheld) implement the following interfaces (respectively): <ul> <li> [sqlite3_mutex_alloc()] </li> <li> [sqlite3_mutex_free()] </li> <li> [sqlite3_mutex_enter()] </li> <li> [sqlite3_mutex_try()] </li> <li> [sqlite3_mutex_leave()] </li> <li> [sqlite3_mutex_held()] </li> <li> [sqlite3_mutex_notheld()] </li> </ul>)^ The only difference is that the public sqlite3_XXX functions enumerated above silently ignore any invocations that pass a NULL pointer instead of a valid mutex handle. The implementations of the methods defined by this structure are not required to handle this case, the results of passing a NULL pointer instead of a valid mutex handle are undefined (i.e. it is acceptable to provide an implementation that segfaults if it is passed a NULL pointer). The xMutexInit() method must be threadsafe. It must be harmless to invoke xMutexInit() multiple times within the same process and without intervening calls to xMutexEnd(). Second and subsequent calls to xMutexInit() must be no-ops. xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()] and its associates). Similarly, xMutexAlloc() must not use SQLite memory allocation for a static mutex. ^However xMutexAlloc() may use SQLite memory allocation for a fast or recursive mutex. ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is called, but only if the prior call to xMutexInit returned SQLITE_OK. If xMutexInit fails in any way, it is expected to clean up after itself ** prior to returning. / typedef struct sqlite3_mutex_methods sqlite3_mutex_methods; struct sqlite3_mutex_methods { int (xMutexInit)(void); int (xMutexEnd)(void); sqlite3_mutex (xMutexAlloc)(int); void (xMutexFree)(sqlite3_mutex ); void (xMutexEnter)(sqlite3_mutex ); int (xMutexTry)(sqlite3_mutex ); void (xMutexLeave)(sqlite3_mutex ); int (xMutexHeld)(sqlite3_mutex ); int (xMutexNotheld)(sqlite3_mutex ); }; / CAPI3REF: Mutex Verification Routines The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines are intended for use inside assert() statements. The SQLite core never uses these routines except inside an assert() and applications are advised to follow the lead of the core. The SQLite core only provides implementations for these routines when it is compiled with the SQLITE_DEBUG flag. External mutex implementations are only required to provide these routines if SQLITE_DEBUG is defined and if NDEBUG is not defined. These routines should return true if the mutex in their argument is held or not held, respectively, by the calling thread. The implementation is not required to provide versions of these routines that actually work. If the implementation does not provide working versions of these routines, it should at least provide stubs that always return true so that one does not get spurious assertion failures. If the argument to sqlite3_mutex_held() is a NULL pointer then the routine should return 1. This seems counter-intuitive since clearly the mutex cannot be held if it does not exist. But the reason the mutex does not exist is because the build is not using mutexes. And we do not want the assert() containing the call to sqlite3_mutex_held() to fail, so a non-zero return is the appropriate thing to do. The sqlite3_mutex_notheld() ** interface should also return 1 when given a NULL pointer. / #ifndef NDEBUG SQLITE_API int SQLITE_STDCALL sqlite3_mutex_held(sqlite3_mutex); SQLITE_API int SQLITE_STDCALL sqlite3_mutex_notheld(sqlite3_mutex); #endif / CAPI3REF: Mutex Types The [sqlite3_mutex_alloc()] interface takes a single argument which is one of these integer constants. The set of static mutexes may change from one SQLite release to the next. Applications that override the built-in mutex logic must be prepared to accommodate additional static mutexes. / #define SQLITE_MUTEX_FAST 0 #define SQLITE_MUTEX_RECURSIVE 1 #define SQLITE_MUTEX_STATIC_MASTER 2 #define SQLITE_MUTEX_STATIC_MEM 3 / sqlite3_malloc() / #define SQLITE_MUTEX_STATIC_MEM2 4 / NOT USED / #define SQLITE_MUTEX_STATIC_OPEN 4 / sqlite3BtreeOpen() / #define SQLITE_MUTEX_STATIC_PRNG 5 / sqlite3_random() / #define SQLITE_MUTEX_STATIC_LRU 6 / lru page list / #define SQLITE_MUTEX_STATIC_LRU2 7 / NOT USED / #define SQLITE_MUTEX_STATIC_PMEM 7 / sqlite3PageMalloc() / #define SQLITE_MUTEX_STATIC_APP1 8 / For use by application / #define SQLITE_MUTEX_STATIC_APP2 9 / For use by application / #define SQLITE_MUTEX_STATIC_APP3 10 / For use by application / / CAPI3REF: Retrieve the mutex for a database connection METHOD: sqlite3 ^This interface returns a pointer the [sqlite3_mutex] object that serializes access to the [database connection] given in the argument when the [threading mode] is Serialized. ^If the [threading mode] is Single-thread or Multi-thread then this routine returns a NULL pointer. / SQLITE_API sqlite3_mutex SQLITE_STDCALL sqlite3_db_mutex(sqlite3); / CAPI3REF: Low-Level Control Of Database Files METHOD: sqlite3 ^The [sqlite3_file_control()] interface makes a direct call to the xFileControl method for the [sqlite3_io_methods] object associated with a particular database identified by the second argument. ^The name of the database is "main" for the main database or "temp" for the TEMP database, or the name that appears after the AS keyword for databases that are added using the [ATTACH] SQL command. ^A NULL pointer can be used in place of "main" to refer to the main database file. ^The third and fourth parameters to this routine are passed directly through to the second and third parameters of the xFileControl method. ^The return value of the xFileControl method becomes the return value of this routine. ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes a pointer to the underlying [sqlite3_file] object to be written into the space pointed to by the 4th parameter. ^The SQLITE_FCNTL_FILE_POINTER case is a short-circuit path which does not actually invoke the underlying sqlite3_io_methods.xFileControl method. ^If the second parameter (zDbName) does not match the name of any open database file, then SQLITE_ERROR is returned. ^This error code is not remembered and will not be recalled by [sqlite3_errcode()] or [sqlite3_errmsg()]. The underlying xFileControl method might also return SQLITE_ERROR. There is no way to distinguish between an incorrect zDbName and an SQLITE_ERROR return from the underlying xFileControl method. ** See also: [SQLITE_FCNTL_LOCKSTATE] / SQLITE_API int SQLITE_STDCALL sqlite3_file_control(sqlite3, const char zDbName, int op, void); /* CAPI3REF: Testing Interface ^The sqlite3_test_control() interface is used to read out internal state of SQLite and to inject faults into SQLite for testing purposes. ^The first parameter is an operation code that determines the number, meaning, and operation of all subsequent parameters. This interface is not for use by applications. It exists solely for verifying the correct operation of the SQLite library. Depending on how the SQLite library is compiled, this interface might not exist. The details of the operation codes, their meanings, the parameters they take, and what they do are all subject to change without notice. Unlike most of the SQLite API, this function is not guaranteed to ** operate consistently from one release to the next. / SQLITE_API int SQLITE_CDECL sqlite3_test_control(int op, ...); / CAPI3REF: Testing Interface Operation Codes These constants are the valid operation code parameters used as the first argument to [sqlite3_test_control()]. These parameters and their meanings are subject to change without notice. These values are for testing purposes only. Applications should not use any of these parameters or the ** [sqlite3_test_control()] interface. / #define SQLITE_TESTCTRL_FIRST 5 #define SQLITE_TESTCTRL_PRNG_SAVE 5 #define SQLITE_TESTCTRL_PRNG_RESTORE 6 #define SQLITE_TESTCTRL_PRNG_RESET 7 #define SQLITE_TESTCTRL_BITVEC_TEST 8 #define SQLITE_TESTCTRL_FAULT_INSTALL 9 #define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS 10 #define SQLITE_TESTCTRL_PENDING_BYTE 11 #define SQLITE_TESTCTRL_ASSERT 12 #define SQLITE_TESTCTRL_ALWAYS 13 #define SQLITE_TESTCTRL_RESERVE 14 #define SQLITE_TESTCTRL_OPTIMIZATIONS 15 #define SQLITE_TESTCTRL_ISKEYWORD 16 #define SQLITE_TESTCTRL_SCRATCHMALLOC 17 #define SQLITE_TESTCTRL_LOCALTIME_FAULT 18 #define SQLITE_TESTCTRL_EXPLAIN_STMT 19 / NOT USED / #define SQLITE_TESTCTRL_NEVER_CORRUPT 20 #define SQLITE_TESTCTRL_VDBE_COVERAGE 21 #define SQLITE_TESTCTRL_BYTEORDER 22 #define SQLITE_TESTCTRL_ISINIT 23 #define SQLITE_TESTCTRL_SORTER_MMAP 24 #define SQLITE_TESTCTRL_IMPOSTER 25 #define SQLITE_TESTCTRL_LAST 25 / CAPI3REF: SQLite Runtime Status ^These interfaces are used to retrieve runtime status information about the performance of SQLite, and optionally to reset various highwater marks. ^The first argument is an integer code for the specific parameter to measure. ^(Recognized integer codes are of the form [status parameters \| SQLITE_STATUS_...].)^ ^The current value of the parameter is returned into pCurrent. * ^The highest recorded value is returned in pHighwater. ^If the * resetFlag is true, then the highest record value is reset after ** pHighwater is written. ^(Some parameters do not record the highest * value. For those parameters ** nothing is written into pHighwater and the resetFlag is ignored.)^ * ^(Other parameters record only the highwater mark and not the current ** value. For these latter parameters nothing is written into pCurrent.)^ * ^The sqlite3_status() and sqlite3_status64() routines return SQLITE_OK on success and a non-zero [error code] on failure. If either the current value or the highwater mark is too large to be represented by a 32-bit integer, then the values returned by sqlite3_status() are undefined. See also: [sqlite3_db_status()] / SQLITE_API int SQLITE_STDCALL sqlite3_status(int op, int pCurrent, int pHighwater, int resetFlag); SQLITE_API int SQLITE_STDCALL sqlite3_status64( int op, sqlite3_int64 pCurrent, sqlite3_int64 pHighwater, int resetFlag ); / CAPI3REF: Status Parameters KEYWORDS: {status parameters} These integer constants designate various run-time status parameters that can be returned by [sqlite3_status()]. <dl> [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt> <dd>This parameter is the current amount of memory checked out using [sqlite3_malloc()], either directly or indirectly. The figure includes calls made to [sqlite3_malloc()] by the application and internal memory usage by the SQLite library. Scratch memory controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in this parameter. The amount returned is the sum of the allocation sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^ [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt> <dd>This parameter records the largest memory allocation request handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their internal equivalents). Only the value returned in the pHighwater parameter to [sqlite3_status()] is of interest. * The value written into the pCurrent parameter is undefined.</dd>)^ * [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt> <dd>This parameter records the number of separate memory allocations currently checked out.</dd>)^ [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt> <dd>This parameter returns the number of pages used out of the [pagecache memory allocator] that was configured using [SQLITE_CONFIG_PAGECACHE]. The value returned is in pages, not in bytes.</dd>)^ [[SQLITE_STATUS_PAGECACHE_OVERFLOW]] ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt> <dd>This parameter returns the number of bytes of page cache allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE] buffer and where forced to overflow to [sqlite3_malloc()]. The returned value includes allocations that overflowed because they where too large (they were larger than the "sz" parameter to [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because no space was left in the page cache.</dd>)^ [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt> <dd>This parameter records the largest memory allocation request handed to [pagecache memory allocator]. Only the value returned in the pHighwater parameter to [sqlite3_status()] is of interest. * The value written into the pCurrent parameter is undefined.</dd>)^ * [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt> <dd>This parameter returns the number of allocations used out of the [scratch memory allocator] configured using [SQLITE_CONFIG_SCRATCH]. The value returned is in allocations, not in bytes. Since a single thread may only have one scratch allocation outstanding at time, this parameter also reports the number of threads using scratch memory at the same time.</dd>)^ [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt> <dd>This parameter returns the number of bytes of scratch memory allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH] buffer and where forced to overflow to [sqlite3_malloc()]. The values returned include overflows because the requested allocation was too larger (that is, because the requested allocation was larger than the "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer slots were available. </dd>)^ [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt> <dd>This parameter records the largest memory allocation request handed to [scratch memory allocator]. Only the value returned in the pHighwater parameter to [sqlite3_status()] is of interest. * The value written into the pCurrent parameter is undefined.</dd>)^ * [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt> <dd>This parameter records the deepest parser stack. It is only meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^ </dl> New status parameters may be added from time to time. / #define SQLITE_STATUS_MEMORY_USED 0 #define SQLITE_STATUS_PAGECACHE_USED 1 #define SQLITE_STATUS_PAGECACHE_OVERFLOW 2 #define SQLITE_STATUS_SCRATCH_USED 3 #define SQLITE_STATUS_SCRATCH_OVERFLOW 4 #define SQLITE_STATUS_MALLOC_SIZE 5 #define SQLITE_STATUS_PARSER_STACK 6 #define SQLITE_STATUS_PAGECACHE_SIZE 7 #define SQLITE_STATUS_SCRATCH_SIZE 8 #define SQLITE_STATUS_MALLOC_COUNT 9 / CAPI3REF: Database Connection Status METHOD: sqlite3 ^This interface is used to retrieve runtime status information about a single [database connection]. ^The first argument is the database connection object to be interrogated. ^The second argument is an integer constant, taken from the set of [SQLITE_DBSTATUS options], that determines the parameter to interrogate. The set of [SQLITE_DBSTATUS options] is likely to grow in future releases of SQLite. ** ^The current value of the requested parameter is written into pCur * and the highest instantaneous value is written into pHiwtr. ^If * the resetFlg is true, then the highest instantaneous value is reset back down to the current value. ^The sqlite3_db_status() routine returns SQLITE_OK on success and a non-zero [error code] on failure. See also: [sqlite3_status()] and [sqlite3_stmt_status()]. / SQLITE_API int SQLITE_STDCALL sqlite3_db_status(sqlite3, int op, int pCur, int pHiwtr, int resetFlg); /* CAPI3REF: Status Parameters for database connections KEYWORDS: {SQLITE_DBSTATUS options} These constants are the available integer "verbs" that can be passed as the second argument to the [sqlite3_db_status()] interface. New verbs may be added in future releases of SQLite. Existing verbs might be discontinued. Applications should check the return code from [sqlite3_db_status()] to make sure that the call worked. The [sqlite3_db_status()] interface will return a non-zero error code if a discontinued or unsupported verb is invoked. <dl> [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt> <dd>This parameter returns the number of lookaside memory slots currently checked out.</dd>)^ [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt> <dd>This parameter returns the number malloc attempts that were satisfied using lookaside memory. Only the high-water value is meaningful; the current value is always zero.)^ [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt> <dd>This parameter returns the number malloc attempts that might have been satisfied using lookaside memory but failed due to the amount of memory requested being larger than the lookaside slot size. Only the high-water value is meaningful; the current value is always zero.)^ [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt> <dd>This parameter returns the number malloc attempts that might have been satisfied using lookaside memory but failed due to all lookaside memory already being in use. Only the high-water value is meaningful; the current value is always zero.)^ [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt> <dd>This parameter returns the approximate number of bytes of heap memory used by all pager caches associated with the database connection.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0. [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt> <dd>This parameter returns the approximate number of bytes of heap memory used to store the schema for all databases associated with the connection - main, temp, and any [ATTACH]-ed databases.)^ ^The full amount of memory used by the schemas is reported, even if the schema memory is shared with other database connections due to [shared cache mode] being enabled. ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0. [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt> <dd>This parameter returns the approximate number of bytes of heap and lookaside memory used by all prepared statements associated with the database connection.)^ ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0. </dd> [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt> <dd>This parameter returns the number of pager cache hits that have occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT is always 0. </dd> [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt> <dd>This parameter returns the number of pager cache misses that have occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS is always 0. </dd> [[SQLITE_DBSTATUS_CACHE_WRITE]] ^(<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt> <dd>This parameter returns the number of dirty cache entries that have been written to disk. Specifically, the number of pages written to the wal file in wal mode databases, or the number of pages written to the database file in rollback mode databases. Any pages written as part of transaction rollback or database recovery operations are not included. If an IO or other error occurs while writing a page to disk, the effect on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0. </dd> [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt> <dd>This parameter returns zero for the current value if and only if all foreign key constraints (deferred or immediate) have been resolved.)^ ^The highwater mark is always 0. </dd> </dl> / #define SQLITE_DBSTATUS_LOOKASIDE_USED 0 #define SQLITE_DBSTATUS_CACHE_USED 1 #define SQLITE_DBSTATUS_SCHEMA_USED 2 #define SQLITE_DBSTATUS_STMT_USED 3 #define SQLITE_DBSTATUS_LOOKASIDE_HIT 4 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE 5 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL 6 #define SQLITE_DBSTATUS_CACHE_HIT 7 #define SQLITE_DBSTATUS_CACHE_MISS 8 #define SQLITE_DBSTATUS_CACHE_WRITE 9 #define SQLITE_DBSTATUS_DEFERRED_FKS 10 #define SQLITE_DBSTATUS_MAX 10 / Largest defined DBSTATUS / / CAPI3REF: Prepared Statement Status METHOD: sqlite3_stmt ^(Each prepared statement maintains various [SQLITE_STMTSTATUS counters] that measure the number of times it has performed specific operations.)^ These counters can be used to monitor the performance characteristics of the prepared statements. For example, if the number of table steps greatly exceeds the number of table searches or result rows, that would tend to indicate that the prepared statement is using a full table scan rather than an index. ^(This interface is used to retrieve and reset counter values from a [prepared statement]. The first argument is the prepared statement object to be interrogated. The second argument is an integer code for a specific [SQLITE_STMTSTATUS counter] to be interrogated.)^ ^The current value of the requested counter is returned. ^If the resetFlg is true, then the counter is reset to zero after this interface call returns. See also: [sqlite3_status()] and [sqlite3_db_status()]. / SQLITE_API int SQLITE_STDCALL sqlite3_stmt_status(sqlite3_stmt, int op,int resetFlg); /* CAPI3REF: Status Parameters for prepared statements KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters} These preprocessor macros define integer codes that name counter values associated with the [sqlite3_stmt_status()] interface. The meanings of the various counters are as follows: <dl> [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt> <dd>^This is the number of times that SQLite has stepped forward in a table as part of a full table scan. Large numbers for this counter may indicate opportunities for performance improvement through careful use of indices.</dd> [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt> <dd>^This is the number of sort operations that have occurred. A non-zero value in this counter may indicate an opportunity to improvement performance through careful use of indices.</dd> [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt> <dd>^This is the number of rows inserted into transient indices that were created automatically in order to help joins run faster. A non-zero value in this counter may indicate an opportunity to improvement performance by adding permanent indices that do not need to be reinitialized each time the statement is run.</dd> [[SQLITE_STMTSTATUS_VM_STEP]] <dt>SQLITE_STMTSTATUS_VM_STEP</dt> <dd>^This is the number of virtual machine operations executed by the prepared statement if that number is less than or equal to 2147483647. The number of virtual machine operations can be used as a proxy for the total work done by the prepared statement. If the number of virtual machine operations exceeds 2147483647 then the value returned by this statement status code is undefined. </dd> ** </dl> / #define SQLITE_STMTSTATUS_FULLSCAN_STEP 1 #define SQLITE_STMTSTATUS_SORT 2 #define SQLITE_STMTSTATUS_AUTOINDEX 3 #define SQLITE_STMTSTATUS_VM_STEP 4 / CAPI3REF: Custom Page Cache Object The sqlite3_pcache type is opaque. It is implemented by the pluggable module. The SQLite core has no knowledge of its size or internal structure and never deals with the sqlite3_pcache object except by holding and passing pointers to the object. ** See [sqlite3_pcache_methods2] for additional information. / typedef struct sqlite3_pcache sqlite3_pcache; / CAPI3REF: Custom Page Cache Object The sqlite3_pcache_page object represents a single page in the page cache. The page cache will allocate instances of this object. Various methods of the page cache use pointers to instances of this object as parameters or as their return value. See [sqlite3_pcache_methods2] for additional information. / typedef struct sqlite3_pcache_page sqlite3_pcache_page; struct sqlite3_pcache_page { void pBuf; /* The content of the page / void pExtra; /* Extra information associated with the page / }; / CAPI3REF: Application Defined Page Cache. KEYWORDS: {page cache} ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can register an alternative page cache implementation by passing in an instance of the sqlite3_pcache_methods2 structure.)^ In many applications, most of the heap memory allocated by SQLite is used for the page cache. By implementing a custom page cache using this API, an application can better control the amount of memory consumed by SQLite, the way in which that memory is allocated and released, and the policies used to determine exactly which parts of a database file are cached and for how long. The alternative page cache mechanism is an extreme measure that is only needed by the most demanding applications. The built-in page cache is recommended for most uses. ^(The contents of the sqlite3_pcache_methods2 structure are copied to an internal buffer by SQLite within the call to [sqlite3_config]. Hence the application may discard the parameter after the call to [sqlite3_config()] returns.)^ [[the xInit() page cache method]] ^(The xInit() method is called once for each effective call to [sqlite3_initialize()])^ (usually only once during the lifetime of the process). ^(The xInit() method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^ The intent of the xInit() method is to set up global data structures required by the custom page cache implementation. ^(If the xInit() method is NULL, then the built-in default page cache is used instead of the application defined page cache.)^ [[the xShutdown() page cache method]] ^The xShutdown() method is called by [sqlite3_shutdown()]. It can be used to clean up any outstanding resources before process shutdown, if required. ^The xShutdown() method may be NULL. ^SQLite automatically serializes calls to the xInit method, so the xInit method need not be threadsafe. ^The xShutdown method is only called from [sqlite3_shutdown()] so it does not need to be threadsafe either. All other methods must be threadsafe in multithreaded applications. ^SQLite will never invoke xInit() more than once without an intervening call to xShutdown(). [[the xCreate() page cache methods]] ^SQLite invokes the xCreate() method to construct a new cache instance. SQLite will typically create one cache instance for each open database file, though this is not guaranteed. ^The first parameter, szPage, is the size in bytes of the pages that must be allocated by the cache. ^szPage will always a power of two. ^The second parameter szExtra is a number of bytes of extra storage associated with each page cache entry. ^The szExtra parameter will a number less than 250. SQLite will use the extra szExtra bytes on each page to store metadata about the underlying database page on disk. The value passed into szExtra depends on the SQLite version, the target platform, and how SQLite was compiled. ^The third argument to xCreate(), bPurgeable, is true if the cache being created will be used to cache database pages of a file stored on disk, or false if it is used for an in-memory database. The cache implementation does not have to do anything special based with the value of bPurgeable; it is purely advisory. ^On a cache where bPurgeable is false, SQLite will never invoke xUnpin() except to deliberately delete a page. ^In other words, calls to xUnpin() on a cache with bPurgeable set to false will always have the "discard" flag set to true. ^Hence, a cache created with bPurgeable false will never contain any unpinned pages. [[the xCachesize() page cache method]] ^(The xCachesize() method may be called at any time by SQLite to set the suggested maximum cache-size (number of pages stored by) the cache instance passed as the first argument. This is the value configured using the SQLite "[PRAGMA cache_size]" command.)^ As with the bPurgeable parameter, the implementation is not required to do anything with this value; it is advisory only. [[the xPagecount() page cache methods]] The xPagecount() method must return the number of pages currently stored in the cache, both pinned and unpinned. [[the xFetch() page cache methods]] The xFetch() method locates a page in the cache and returns a pointer to an sqlite3_pcache_page object associated with that page, or a NULL pointer. The pBuf element of the returned sqlite3_pcache_page object will be a pointer to a buffer of szPage bytes used to store the content of a single database page. The pExtra element of sqlite3_pcache_page will be a pointer to the szExtra bytes of extra storage that SQLite has requested for each entry in the page cache. The page to be fetched is determined by the key. ^The minimum key value is 1. After it has been retrieved using xFetch, the page is considered to be "pinned". If the requested page is already in the page cache, then the page cache implementation must return a pointer to the page buffer with its content intact. If the requested page is not already in the cache, then the cache implementation should use the value of the createFlag parameter to help it determined what action to take: <table border=1 width=85% align=center> <tr><th> createFlag <th> Behavior when page is not already in cache <tr><td> 0 <td> Do not allocate a new page. Return NULL. <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so. Otherwise return NULL. <tr><td> 2 <td> Make every effort to allocate a new page. Only return NULL if allocating a new page is effectively impossible. </table> ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1. SQLite will only use a createFlag of 2 after a prior call with a createFlag of 1 failed.)^ In between the to xFetch() calls, SQLite may attempt to unpin one or more cache pages by spilling the content of pinned pages to disk and synching the operating system disk cache. [[the xUnpin() page cache method]] ^xUnpin() is called by SQLite with a pointer to a currently pinned page as its second argument. If the third parameter, discard, is non-zero, then the page must be evicted from the cache. ^If the discard parameter is zero, then the page may be discarded or retained at the discretion of page cache implementation. ^The page cache implementation may choose to evict unpinned pages at any time. The cache must not perform any reference counting. A single call to xUnpin() unpins the page regardless of the number of prior calls to xFetch(). [[the xRekey() page cache methods]] The xRekey() method is used to change the key value associated with the page passed as the second argument. If the cache previously contains an entry associated with newKey, it must be discarded. ^Any prior cache entry associated with newKey is guaranteed not to be pinned. When SQLite calls the xTruncate() method, the cache must discard all existing cache entries with page numbers (keys) greater than or equal to the value of the iLimit parameter passed to xTruncate(). If any of these pages are pinned, they are implicitly unpinned, meaning that they can be safely discarded. [[the xDestroy() page cache method]] ^The xDestroy() method is used to delete a cache allocated by xCreate(). All resources associated with the specified cache should be freed. ^After ** calling the xDestroy() method, SQLite considers the [sqlite3_pcache] * handle invalid, and will not use it with any other sqlite3_pcache_methods2 functions. [[the xShrink() page cache method]] ^SQLite invokes the xShrink() method when it wants the page cache to free up as much of heap memory as possible. The page cache implementation is not obligated to free any memory, but well-behaved implementations should ** do their best. / typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2; struct sqlite3_pcache_methods2 { int iVersion; void pArg; int (xInit)(void); void (xShutdown)(void); sqlite3_pcache (xCreate)(int szPage, int szExtra, int bPurgeable); void (xCachesize)(sqlite3_pcache, int nCachesize); int (xPagecount)(sqlite3_pcache); sqlite3_pcache_page (xFetch)(sqlite3_pcache, unsigned key, int createFlag); void (xUnpin)(sqlite3_pcache, sqlite3_pcache_page, int discard); void (xRekey)(sqlite3_pcache, sqlite3_pcache_page, unsigned oldKey, unsigned newKey); void (xTruncate)(sqlite3_pcache, unsigned iLimit); void (xDestroy)(sqlite3_pcache); void (xShrink)(sqlite3_pcache); }; / This is the obsolete pcache_methods object that has now been replaced by sqlite3_pcache_methods2. This object is not used by SQLite. It is ** retained in the header file for backwards compatibility only. / typedef struct sqlite3_pcache_methods sqlite3_pcache_methods; struct sqlite3_pcache_methods { void pArg; int (xInit)(void); void (xShutdown)(void); sqlite3_pcache (xCreate)(int szPage, int bPurgeable); void (xCachesize)(sqlite3_pcache, int nCachesize); int (xPagecount)(sqlite3_pcache); void (xFetch)(sqlite3_pcache, unsigned key, int createFlag); void (xUnpin)(sqlite3_pcache, void, int discard); void (xRekey)(sqlite3_pcache, void, unsigned oldKey, unsigned newKey); void (xTruncate)(sqlite3_pcache, unsigned iLimit); void (xDestroy)(sqlite3_pcache); }; / CAPI3REF: Online Backup Object The sqlite3_backup object records state information about an ongoing online backup operation. ^The sqlite3_backup object is created by a call to [sqlite3_backup_init()] and is destroyed by a call to [sqlite3_backup_finish()]. See Also: [Using the SQLite Online Backup API] / typedef struct sqlite3_backup sqlite3_backup; / CAPI3REF: Online Backup API. The backup API copies the content of one database into another. It is useful either for creating backups of databases or for copying in-memory databases to or from persistent files. See Also: [Using the SQLite Online Backup API] ^SQLite holds a write transaction open on the destination database file for the duration of the backup operation. ^The source database is read-locked only while it is being read; it is not locked continuously for the entire backup operation. ^Thus, the backup may be performed on a live source database without preventing other database connections from reading or writing to the source database while the backup is underway. ^(To perform a backup operation: <ol> <li><b>sqlite3_backup_init()</b> is called once to initialize the backup, <li><b>sqlite3_backup_step()</b> is called one or more times to transfer the data between the two databases, and finally <li><b>sqlite3_backup_finish()</b> is called to release all resources associated with the backup operation. </ol>)^ There should be exactly one call to sqlite3_backup_finish() for each successful call to sqlite3_backup_init(). [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b> ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the [database connection] associated with the destination database and the database name, respectively. ^The database name is "main" for the main database, "temp" for the temporary database, or the name specified after the AS keyword in an [ATTACH] statement for an attached database. ^The S and M arguments passed to sqlite3_backup_init(D,N,S,M) identify the [database connection] and database name of the source database, respectively. ^The source and destination [database connections] (parameters S and D) must be different or else sqlite3_backup_init(D,N,S,M) will fail with an error. ^A call to sqlite3_backup_init() will fail, returning SQLITE_ERROR, if there is already a read or read-write transaction open on the destination database. ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is returned and an error code and error message are stored in the destination [database connection] D. ^The error code and message for the failed call to sqlite3_backup_init() can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or [sqlite3_errmsg16()] functions. ^A successful call to sqlite3_backup_init() returns a pointer to an [sqlite3_backup] object. ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and sqlite3_backup_finish() functions to perform the specified backup operation. [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b> ^Function sqlite3_backup_step(B,N) will copy up to N pages between the source and destination databases specified by [sqlite3_backup] object B. ^If N is negative, all remaining source pages are copied. ^If sqlite3_backup_step(B,N) successfully copies N pages and there are still more pages to be copied, then the function returns [SQLITE_OK]. ^If sqlite3_backup_step(B,N) successfully finishes copying all pages from source to destination, then it returns [SQLITE_DONE]. ^If an error occurs while running sqlite3_backup_step(B,N), then an [error code] is returned. ^As well as [SQLITE_OK] and [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY], [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an [SQLITE_IOERR_ACCESS \| SQLITE_IOERR_XXX] extended error code. ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if <ol> <li> the destination database was opened read-only, or <li> the destination database is using write-ahead-log journaling and the destination and source page sizes differ, or <li> the destination database is an in-memory database and the destination and source page sizes differ. </ol>)^ ^If sqlite3_backup_step() cannot obtain a required file-system lock, then the [sqlite3_busy_handler \| busy-handler function] is invoked (if one is specified). ^If the busy-handler returns non-zero before the lock is available, then [SQLITE_BUSY] is returned to the caller. ^In this case the call to sqlite3_backup_step() can be retried later. ^If the source [database connection] is being used to write to the source database when sqlite3_backup_step() is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this case the call to sqlite3_backup_step() can be retried later on. ^(If [SQLITE_IOERR_ACCESS \| SQLITE_IOERR_XXX], [SQLITE_NOMEM], or [SQLITE_READONLY] is returned, then there is no point in retrying the call to sqlite3_backup_step(). These errors are considered fatal.)^ The application must accept that the backup operation has failed and pass the backup operation handle to the sqlite3_backup_finish() to release associated resources. ^The first call to sqlite3_backup_step() obtains an exclusive lock on the destination file. ^The exclusive lock is not released until either sqlite3_backup_finish() is called or the backup operation is complete and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to sqlite3_backup_step() obtains a [shared lock] on the source database that lasts for the duration of the sqlite3_backup_step() call. ^Because the source database is not locked between calls to sqlite3_backup_step(), the source database may be modified mid-way through the backup process. ^If the source database is modified by an external process or via a database connection other than the one being used by the backup operation, then the backup will be automatically restarted by the next call to sqlite3_backup_step(). ^If the source database is modified by the using the same database connection as is used by the backup operation, then the backup database is automatically updated at the same time. [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b> When sqlite3_backup_step() has returned [SQLITE_DONE], or when the application wishes to abandon the backup operation, the application should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish(). ^The sqlite3_backup_finish() interfaces releases all resources associated with the [sqlite3_backup] object. ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any active write-transaction on the destination database is rolled back. The [sqlite3_backup] object is invalid and may not be used following a call to sqlite3_backup_finish(). ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no sqlite3_backup_step() errors occurred, regardless or whether or not sqlite3_backup_step() completed. ^If an out-of-memory condition or IO error occurred during any prior sqlite3_backup_step() call on the same [sqlite3_backup] object, then sqlite3_backup_finish() returns the corresponding [error code]. ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step() is not a permanent error and does not affect the return value of sqlite3_backup_finish(). [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]] <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b> ^The sqlite3_backup_remaining() routine returns the number of pages still to be backed up at the conclusion of the most recent sqlite3_backup_step(). ^The sqlite3_backup_pagecount() routine returns the total number of pages in the source database at the conclusion of the most recent sqlite3_backup_step(). ^(The values returned by these functions are only updated by sqlite3_backup_step(). If the source database is modified in a way that changes the size of the source database or the number of pages remaining, those changes are not reflected in the output of sqlite3_backup_pagecount() and sqlite3_backup_remaining() until after the next sqlite3_backup_step().)^ <b>Concurrent Usage of Database Handles</b> ^The source [database connection] may be used by the application for other purposes while a backup operation is underway or being initialized. ^If SQLite is compiled and configured to support threadsafe database connections, then the source database connection may be used concurrently from within other threads. However, the application must guarantee that the destination [database connection] is not passed to any other API (by any thread) after sqlite3_backup_init() is called and before the corresponding call to sqlite3_backup_finish(). SQLite does not currently check to see if the application incorrectly accesses the destination [database connection] and so no error code is reported, but the operations may malfunction nevertheless. Use of the destination database connection while a backup is in progress might also also cause a mutex deadlock. If running in [shared cache mode], the application must guarantee that the shared cache used by the destination database is not accessed while the backup is running. In practice this means that the application must guarantee that the disk file being backed up to is not accessed by any connection within the process, not just the specific connection that was passed to sqlite3_backup_init(). The [sqlite3_backup] object itself is partially threadsafe. Multiple threads may safely make multiple concurrent calls to sqlite3_backup_step(). However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount() APIs are not strictly speaking threadsafe. If they are invoked at the same time as another thread is invoking sqlite3_backup_step() it is possible that they return invalid values. / SQLITE_API sqlite3_backup SQLITE_STDCALL sqlite3_backup_init( sqlite3 pDest, / Destination database handle / const char zDestName, /* Destination database name / sqlite3 pSource, /* Source database handle / const char zSourceName /* Source database name / ); SQLITE_API int SQLITE_STDCALL sqlite3_backup_step(sqlite3_backup p, int nPage); SQLITE_API int SQLITE_STDCALL sqlite3_backup_finish(sqlite3_backup p); SQLITE_API int SQLITE_STDCALL sqlite3_backup_remaining(sqlite3_backup p); SQLITE_API int SQLITE_STDCALL sqlite3_backup_pagecount(sqlite3_backup p); / CAPI3REF: Unlock Notification METHOD: sqlite3 ^When running in shared-cache mode, a database operation may fail with an [SQLITE_LOCKED] error if the required locks on the shared-cache or individual tables within the shared-cache cannot be obtained. See [SQLite Shared-Cache Mode] for a description of shared-cache locking. ^This API may be used to register a callback that SQLite will invoke when the connection currently holding the required lock relinquishes it. ^This API is only available if the library was compiled with the [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined. See Also: [Using the SQLite Unlock Notification Feature]. ^Shared-cache locks are released when a database connection concludes its current transaction, either by committing it or rolling it back. ^When a connection (known as the blocked connection) fails to obtain a shared-cache lock and SQLITE_LOCKED is returned to the caller, the identity of the database connection (the blocking connection) that has locked the required resource is stored internally. ^After an application receives an SQLITE_LOCKED error, it may call the sqlite3_unlock_notify() method with the blocked connection handle as the first argument to register for a callback that will be invoked when the blocking connections current transaction is concluded. ^The callback is invoked from within the [sqlite3_step] or [sqlite3_close] call that concludes the blocking connections transaction. ^(If sqlite3_unlock_notify() is called in a multi-threaded application, there is a chance that the blocking connection will have already concluded its transaction by the time sqlite3_unlock_notify() is invoked. If this happens, then the specified callback is invoked immediately, from within the call to sqlite3_unlock_notify().)^ ^If the blocked connection is attempting to obtain a write-lock on a shared-cache table, and more than one other connection currently holds a read-lock on the same table, then SQLite arbitrarily selects one of the other connections to use as the blocking connection. ^(There may be at most one unlock-notify callback registered by a blocked connection. If sqlite3_unlock_notify() is called when the blocked connection already has a registered unlock-notify callback, then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is called with a NULL pointer as its second argument, then any existing unlock-notify callback is canceled. ^The blocked connections unlock-notify callback may also be canceled by closing the blocked connection using [sqlite3_close()]. The unlock-notify callback is not reentrant. If an application invokes any sqlite3_xxx API functions from within an unlock-notify callback, a crash or deadlock may be the result. ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always returns SQLITE_OK. <b>Callback Invocation Details</b> When an unlock-notify callback is registered, the application provides a ** single void* pointer that is passed to the callback when it is invoked. However, the signature of the callback function allows SQLite to pass it an array of void* context pointers. The first argument passed to ** an unlock-notify callback is a pointer to an array of void* pointers, and the second is the number of entries in the array. When a blocking connections transaction is concluded, there may be more than one blocked connection that has registered for an unlock-notify callback. ^If two or more such blocked connections have specified the same callback function, then instead of invoking the callback function ** multiple times, it is invoked once with the set of void* context pointers specified by the blocked connections bundled together into an array. This gives the application an opportunity to prioritize any actions related to the set of unblocked database connections. <b>Deadlock Detection</b> Assuming that after registering for an unlock-notify callback a database waits for the callback to be issued before taking any further action (a reasonable assumption), then using this API may cause the application to deadlock. For example, if connection X is waiting for connection Y's transaction to be concluded, and similarly connection Y is waiting on connection X's transaction, then neither connection will proceed and the system may remain deadlocked indefinitely. To avoid this scenario, the sqlite3_unlock_notify() performs deadlock detection. ^If a given call to sqlite3_unlock_notify() would put the system in a deadlocked state, then SQLITE_LOCKED is returned and no unlock-notify callback is registered. The system is said to be in a deadlocked state if connection A has registered for an unlock-notify callback on the conclusion of connection B's transaction, and connection B has itself registered for an unlock-notify callback when connection A's transaction is concluded. ^Indirect deadlock is also detected, so the system is also considered to be deadlocked if connection B has registered for an unlock-notify callback on the conclusion of connection C's transaction, where connection C is waiting on connection A. ^Any number of levels of indirection are allowed. <b>The "DROP TABLE" Exception</b> When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost always appropriate to call sqlite3_unlock_notify(). There is however, one exception. When executing a "DROP TABLE" or "DROP INDEX" statement, SQLite checks if there are any currently executing SELECT statements that belong to the same connection. If there are, SQLITE_LOCKED is returned. In this case there is no "blocking connection", so invoking sqlite3_unlock_notify() results in the unlock-notify callback being invoked immediately. If the application then re-attempts the "DROP TABLE" or "DROP INDEX" query, an infinite loop might be the result. One way around this problem is to check the extended error code returned by an sqlite3_step() call. ^(If there is a blocking connection, then the extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in the special "DROP TABLE/INDEX" case, the extended error code is just SQLITE_LOCKED.)^ / SQLITE_API int SQLITE_STDCALL sqlite3_unlock_notify( sqlite3 pBlocked, /* Waiting connection / void (xNotify)(void *apArg, int nArg), / Callback function to invoke / void pNotifyArg /* Argument to pass to xNotify / ); / CAPI3REF: String Comparison ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications and extensions to compare the contents of two buffers containing UTF-8 strings in a case-independent fashion, using the same definition of "case independence" that SQLite uses internally when comparing identifiers. / SQLITE_API int SQLITE_STDCALL sqlite3_stricmp(const char , const char ); SQLITE_API int SQLITE_STDCALL sqlite3_strnicmp(const char , const char , int); / ** CAPI3REF: String Globbing * ^The [sqlite3_strglob(P,X)] interface returns zero if string X matches the glob pattern P, and it returns non-zero if string X does not match the glob pattern P. ^The definition of glob pattern matching used in [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the SQL dialect used by SQLite. ^The sqlite3_strglob(P,X) function is case sensitive. Note that this routine returns zero on a match and non-zero if the strings ** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()]. / SQLITE_API int SQLITE_STDCALL sqlite3_strglob(const char zGlob, const char zStr); / CAPI3REF: Error Logging Interface ^The [sqlite3_log()] interface writes a message into the [error log] established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()]. ^If logging is enabled, the zFormat string and subsequent arguments are used with [sqlite3_snprintf()] to generate the final output string. The sqlite3_log() interface is intended for use by extensions such as virtual tables, collating functions, and SQL functions. While there is nothing to prevent an application from calling sqlite3_log(), doing so is considered bad form. The zFormat string must not be NULL. To avoid deadlocks and other threading problems, the sqlite3_log() routine will not use dynamically allocated memory. The log message is stored in a fixed-length buffer on the stack. If the log message is longer than a few hundred characters, it will be truncated to the length of the ** buffer. / SQLITE_API void SQLITE_CDECL sqlite3_log(int iErrCode, const char zFormat, ...); /* CAPI3REF: Write-Ahead Log Commit Hook METHOD: sqlite3 ^The [sqlite3_wal_hook()] function is used to register a callback that is invoked each time data is committed to a database in wal mode. ^(The callback is invoked by SQLite after the commit has taken place and the associated write-lock on the database released)^, so the implementation may read, write or [checkpoint] the database as required. ^The first parameter passed to the callback function when it is invoked is a copy of the third parameter passed to sqlite3_wal_hook() when registering the callback. ^The second is a copy of the database handle. ^The third parameter is the name of the database that was written to - either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter is the number of pages currently in the write-ahead log file, including those that were just committed. The callback function should normally return [SQLITE_OK]. ^If an error code is returned, that error will propagate back up through the SQLite code base to cause the statement that provoked the callback to report an error, though the commit will have still occurred. If the callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value that does not correspond to any valid SQLite error code, the results are undefined. A single database handle may have at most a single write-ahead log callback registered at one time. ^Calling [sqlite3_wal_hook()] replaces any previously registered write-ahead log callback. ^Note that the [sqlite3_wal_autocheckpoint()] interface and the [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will those overwrite any prior [sqlite3_wal_hook()] settings. / SQLITE_API void SQLITE_STDCALL sqlite3_wal_hook( sqlite3, int()(void ,sqlite3,const char,int), void ); /* CAPI3REF: Configure an auto-checkpoint METHOD: sqlite3 ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around [sqlite3_wal_hook()] that causes any database on [database connection] D to automatically [checkpoint] after committing a transaction if there are N or more frames in the [write-ahead log] file. ^Passing zero or a negative value as the nFrame parameter disables automatic checkpoints entirely. ^The callback registered by this function replaces any existing callback registered using [sqlite3_wal_hook()]. ^Likewise, registering a callback using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism configured by this function. ^The [wal_autocheckpoint pragma] can be used to invoke this interface from SQL. ^Checkpoints initiated by this mechanism are [sqlite3_wal_checkpoint_v2\|PASSIVE]. ^Every new [database connection] defaults to having the auto-checkpoint enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT] pages. The use of this interface is only necessary if the default setting is found to be suboptimal ** for a particular application. / SQLITE_API int SQLITE_STDCALL sqlite3_wal_autocheckpoint(sqlite3 db, int N); /* CAPI3REF: Checkpoint a database METHOD: sqlite3 ^(The sqlite3_wal_checkpoint(D,X) is equivalent to [sqlite3_wal_checkpoint_v2](D,X,[SQLITE_CHECKPOINT_PASSIVE],0,0).)^ In brief, sqlite3_wal_checkpoint(D,X) causes the content in the [write-ahead log] for database X on [database connection] D to be transferred into the database file and for the write-ahead log to be reset. See the [checkpointing] documentation for addition information. This interface used to be the only way to cause a checkpoint to occur. But then the newer and more powerful [sqlite3_wal_checkpoint_v2()] interface was added. This interface is retained for backwards compatibility and as a convenience for applications that need to manually start a callback but which do not need the full power (and corresponding complication) of [sqlite3_wal_checkpoint_v2()]. / SQLITE_API int SQLITE_STDCALL sqlite3_wal_checkpoint(sqlite3 db, const char zDb); / CAPI3REF: Checkpoint a database METHOD: sqlite3 ^(The sqlite3_wal_checkpoint_v2(D,X,M,L,C) interface runs a checkpoint operation on database X of [database connection] D in mode M. Status information is written back into integers pointed to by L and C.)^ ^(The M parameter must be a valid [checkpoint mode]:)^ <dl> <dt>SQLITE_CHECKPOINT_PASSIVE<dd> ^Checkpoint as many frames as possible without waiting for any database readers or writers to finish, then sync the database file if all frames in the log were checkpointed. ^The [busy-handler callback] is never invoked in the SQLITE_CHECKPOINT_PASSIVE mode. ^On the other hand, passive mode might leave the checkpoint unfinished if there are concurrent readers or writers. <dt>SQLITE_CHECKPOINT_FULL<dd> ^This mode blocks (it invokes the [sqlite3_busy_handler\|busy-handler callback]) until there is no database writer and all readers are reading from the most recent database snapshot. ^It then checkpoints all frames in the log file and syncs the database file. ^This mode blocks new database writers while it is pending, but new database readers are allowed to continue unimpeded. <dt>SQLITE_CHECKPOINT_RESTART<dd> ^This mode works the same way as SQLITE_CHECKPOINT_FULL with the addition that after checkpointing the log file it blocks (calls the [busy-handler callback]) until all readers are reading from the database file only. ^This ensures that the next writer will restart the log file from the beginning. ^Like SQLITE_CHECKPOINT_FULL, this mode blocks new database writer attempts while it is pending, but does not impede readers. <dt>SQLITE_CHECKPOINT_TRUNCATE<dd> ^This mode works the same way as SQLITE_CHECKPOINT_RESTART with the addition that it also truncates the log file to zero bytes just prior to a successful return. </dl> ** ^If pnLog is not NULL, then pnLog is set to the total number of frames in * the log file or to -1 if the checkpoint could not run because of an error or because the database is not in [WAL mode]. ^If pnCkpt is not NULL,then pnCkpt is set to the total number of checkpointed frames in the * log file (including any that were already checkpointed before the function was called) or to -1 if the checkpoint could not run due to an error or because the database is not in WAL mode. ^Note that upon successful completion of an SQLITE_CHECKPOINT_TRUNCATE, the log file will have been truncated to zero bytes and so both pnLog and pnCkpt will be set to zero. ^All calls obtain an exclusive "checkpoint" lock on the database file. ^If any other process is running a checkpoint operation at the same time, the lock cannot be obtained and SQLITE_BUSY is returned. ^Even if there is a busy-handler configured, it will not be invoked in this case. ^The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the exclusive "writer" lock on the database file. ^If the writer lock cannot be obtained immediately, and a busy-handler is configured, it is invoked and the writer lock retried until either the busy-handler returns 0 or the lock is successfully obtained. ^The busy-handler is also invoked while waiting for database readers as described above. ^If the busy-handler returns 0 before the writer lock is obtained or while waiting for database readers, the checkpoint operation proceeds from that point in the same way as SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible without blocking any further. ^SQLITE_BUSY is returned in this case. ^If parameter zDb is NULL or points to a zero length string, then the specified operation is attempted on all WAL databases [attached] to [database connection] db. In this case the ** values written to output parameters pnLog and pnCkpt are undefined. ^If an SQLITE_BUSY error is encountered when processing one or more of the attached WAL databases, the operation is still attempted on any remaining attached databases and SQLITE_BUSY is returned at the end. ^If any other error occurs while processing an attached database, processing is abandoned and the error code is returned to the caller immediately. ^If no error (SQLITE_BUSY or otherwise) is encountered while processing the attached databases, SQLITE_OK is returned. ^If database zDb is the name of an attached database that is not in WAL mode, SQLITE_OK is returned and both pnLog and pnCkpt set to -1. ^If zDb is not NULL (or a zero length string) and is not the name of any attached database, SQLITE_ERROR is returned to the caller. ^Unless it returns SQLITE_MISUSE, the sqlite3_wal_checkpoint_v2() interface sets the error information that is queried by [sqlite3_errcode()] and [sqlite3_errmsg()]. ^The [PRAGMA wal_checkpoint] command can be used to invoke this interface from SQL. / SQLITE_API int SQLITE_STDCALL sqlite3_wal_checkpoint_v2( sqlite3 db, /* Database handle / const char zDb, /* Name of attached database (or NULL) / int eMode, / SQLITE_CHECKPOINT_* value / int pnLog, /* OUT: Size of WAL log in frames / int pnCkpt /* OUT: Total number of frames checkpointed / ); / CAPI3REF: Checkpoint Mode Values KEYWORDS: {checkpoint mode} These constants define all valid values for the "checkpoint mode" passed as the third parameter to the [sqlite3_wal_checkpoint_v2()] interface. See the [sqlite3_wal_checkpoint_v2()] documentation for details on the ** meaning of each of these checkpoint modes. / #define SQLITE_CHECKPOINT_PASSIVE 0 / Do as much as possible w/o blocking / #define SQLITE_CHECKPOINT_FULL 1 / Wait for writers, then checkpoint / #define SQLITE_CHECKPOINT_RESTART 2 / Like FULL but wait for for readers / #define SQLITE_CHECKPOINT_TRUNCATE 3 / Like RESTART but also truncate WAL / / CAPI3REF: Virtual Table Interface Configuration This function may be called by either the [xConnect] or [xCreate] method of a [virtual table] implementation to configure various facets of the virtual table interface. If this interface is invoked outside the context of an xConnect or xCreate virtual table method then the behavior is undefined. At present, there is only one option that may be configured using this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].) Further options may be added in the future. / SQLITE_API int SQLITE_CDECL sqlite3_vtab_config(sqlite3, int op, ...); /* CAPI3REF: Virtual Table Configuration Options These macros define the various options to the [sqlite3_vtab_config()] interface that [virtual table] implementations can use to customize and optimize their behavior. <dl> <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT <dd>Calls of the form [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported, where X is an integer. If X is zero, then the [virtual table] whose [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not support constraints. In this configuration (which is the default) if a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire statement is rolled back as if [ON CONFLICT \| OR ABORT] had been specified as part of the users SQL statement, regardless of the actual ON CONFLICT mode specified. If X is non-zero, then the virtual table implementation guarantees that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before any modifications to internal or persistent data structures have been made. If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite is able to roll back a statement or database transaction, and abandon or continue processing the current SQL statement as appropriate. If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode had been ABORT. Virtual table implementations that are required to handle OR REPLACE must do so within the [xUpdate] method. If a call to the [sqlite3_vtab_on_conflict()] function indicates that the current ON CONFLICT policy is REPLACE, the virtual table implementation should silently replace the appropriate rows within the xUpdate callback and return SQLITE_OK. Or, if this is not possible, it may return SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT constraint handling. ** </dl> / #define SQLITE_VTAB_CONSTRAINT_SUPPORT 1 / CAPI3REF: Determine The Virtual Table Conflict Policy This function may only be called from within a call to the [xUpdate] method of a [virtual table] implementation for an INSERT or UPDATE operation. ^The value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL], [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode of the SQL statement that triggered the call to the [xUpdate] method of the [virtual table]. / SQLITE_API int SQLITE_STDCALL sqlite3_vtab_on_conflict(sqlite3 ); /* CAPI3REF: Conflict resolution modes KEYWORDS: {conflict resolution mode} These constants are returned by [sqlite3_vtab_on_conflict()] to inform a [virtual table] implementation what the [ON CONFLICT] mode is for the SQL statement being evaluated. Note that the [SQLITE_IGNORE] constant is also used as a potential return value from the [sqlite3_set_authorizer()] callback and that [SQLITE_ABORT] is also a [result code]. / #define SQLITE_ROLLBACK 1 / #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback / #define SQLITE_FAIL 3 / #define SQLITE_ABORT 4 // Also an error code / #define SQLITE_REPLACE 5 / CAPI3REF: Prepared Statement Scan Status Opcodes KEYWORDS: {scanstatus options} The following constants can be used for the T parameter to the [sqlite3_stmt_scanstatus(S,X,T,V)] interface. Each constant designates a different metric for sqlite3_stmt_scanstatus() to return. When the value returned to V is a string, space to hold that string is managed by the prepared statement S and will be automatically freed when S is finalized. <dl> [[SQLITE_SCANSTAT_NLOOP]] <dt>SQLITE_SCANSTAT_NLOOP</dt> <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set to the total number of times that the X-th loop has run.</dd> [[SQLITE_SCANSTAT_NVISIT]] <dt>SQLITE_SCANSTAT_NVISIT</dt> <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set to the total number of rows examined by all iterations of the X-th loop.</dd> [[SQLITE_SCANSTAT_EST]] <dt>SQLITE_SCANSTAT_EST</dt> <dd>^The "double" variable pointed to by the T parameter will be set to the query planner's estimate for the average number of rows output from each iteration of the X-th loop. If the query planner's estimates was accurate, then this value will approximate the quotient NVISIT/NLOOP and the product of this value for all prior loops with the same SELECTID will be the NLOOP value for the current loop. [[SQLITE_SCANSTAT_NAME]] <dt>SQLITE_SCANSTAT_NAME</dt> <dd>^The "const char " variable pointed to by the T parameter will be set * to a zero-terminated UTF-8 string containing the name of the index or table used for the X-th loop. [[SQLITE_SCANSTAT_EXPLAIN]] <dt>SQLITE_SCANSTAT_EXPLAIN</dt> <dd>^The "const char " variable pointed to by the T parameter will be set * to a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN] description for the X-th loop. [[SQLITE_SCANSTAT_SELECTID]] <dt>SQLITE_SCANSTAT_SELECT</dt> <dd>^The "int" variable pointed to by the T parameter will be set to the "select-id" for the X-th loop. The select-id identifies which query or subquery the loop is part of. The main query has a select-id of zero. The select-id is the same value as is output in the first column of an [EXPLAIN QUERY PLAN] query. ** </dl> / #define SQLITE_SCANSTAT_NLOOP 0 #define SQLITE_SCANSTAT_NVISIT 1 #define SQLITE_SCANSTAT_EST 2 #define SQLITE_SCANSTAT_NAME 3 #define SQLITE_SCANSTAT_EXPLAIN 4 #define SQLITE_SCANSTAT_SELECTID 5 / CAPI3REF: Prepared Statement Scan Status METHOD: sqlite3_stmt This interface returns information about the predicted and measured performance for pStmt. Advanced applications can use this interface to compare the predicted and the measured performance and issue warnings and/or rerun [ANALYZE] if discrepancies are found. Since this interface is expected to be rarely used, it is only available if SQLite is compiled using the [SQLITE_ENABLE_STMT_SCANSTATUS] compile-time option. The "iScanStatusOp" parameter determines which status information to return. The "iScanStatusOp" must be one of the [scanstatus options] or the behavior of this interface is undefined. ^The requested measurement is written into a variable pointed to by the "pOut" parameter. Parameter "idx" identifies the specific loop to retrieve statistics for. Loops are numbered starting from zero. ^If idx is out of range - less than zero or greater than or equal to the total number of loops used to implement the statement - a non-zero value is returned and the variable that pOut points to is unchanged. ^Statistics might not be available for all loops in all statements. ^In cases where there exist loops with no available statistics, this function behaves as if the loop did not exist - it returns non-zero and leave the variable that pOut points to unchanged. ** See also: [sqlite3_stmt_scanstatus_reset()] / SQLITE_API SQLITE_EXPERIMENTAL int SQLITE_STDCALL sqlite3_stmt_scanstatus( sqlite3_stmt pStmt, /* Prepared statement for which info desired / int idx, / Index of loop to report on / int iScanStatusOp, / Information desired. SQLITE_SCANSTAT_* / void pOut /* Result written here / ); / CAPI3REF: Zero Scan-Status Counters METHOD: sqlite3_stmt ^Zero all [sqlite3_stmt_scanstatus()] related event counters. This API is only available if the library is built with pre-processor ** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined. / SQLITE_API SQLITE_EXPERIMENTAL void SQLITE_STDCALL sqlite3_stmt_scanstatus_reset(sqlite3_stmt); /* Undo the hack that converts floating point types to integer for builds on processors without floating point support. / #ifdef SQLITE_OMIT_FLOATING_POINT # undef double #endif #ifdef __cplusplus } / End of the 'extern "C"' block / #endif #endif / _SQLITE3_H_ / / 2010 August 30 The author disclaims copyright to this source code. In place of a legal notice, here is a blessing: May you do good and not evil. May you find forgiveness for yourself and forgive others. May you share freely, never taking more than you give. *********************************************************************** / #ifndef _SQLITE3RTREE_H_ #define _SQLITE3RTREE_H_ #ifdef __cplusplus extern "C" { #endif typedef struct sqlite3_rtree_geometry sqlite3_rtree_geometry; typedef struct sqlite3_rtree_query_info sqlite3_rtree_query_info; / The double-precision datatype used by RTree depends on the ** SQLITE_RTREE_INT_ONLY compile-time option. / #ifdef SQLITE_RTREE_INT_ONLY typedef sqlite3_int64 sqlite3_rtree_dbl; #else typedef double sqlite3_rtree_dbl; #endif / Register a geometry callback named zGeom that can be used as part of an R-Tree geometry query as follows: SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...) / SQLITE_API int SQLITE_STDCALL sqlite3_rtree_geometry_callback( sqlite3 db, const char zGeom, int (xGeom)(sqlite3_rtree_geometry, int, sqlite3_rtree_dbl,int), void pContext ); /* A pointer to a structure of the following type is passed as the first argument to callbacks registered using rtree_geometry_callback(). / struct sqlite3_rtree_geometry { void pContext; /* Copy of pContext passed to s_r_g_c() / int nParam; / Size of array aParam[] / sqlite3_rtree_dbl aParam; /* Parameters passed to SQL geom function / void pUser; /* Callback implementation user data / void (xDelUser)(void ); / Called by SQLite to clean up pUser / }; / Register a 2nd-generation geometry callback named zScore that can be used as part of an R-Tree geometry query as follows: SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zQueryFunc(... params ...) / SQLITE_API int SQLITE_STDCALL sqlite3_rtree_query_callback( sqlite3 db, const char zQueryFunc, int (xQueryFunc)(sqlite3_rtree_query_info), void pContext, void (xDestructor)(void) ); /* A pointer to a structure of the following type is passed as the argument to scored geometry callback registered using sqlite3_rtree_query_callback(). Note that the first 5 fields of this structure are identical to sqlite3_rtree_geometry. This structure is a subclass of ** sqlite3_rtree_geometry. / struct sqlite3_rtree_query_info { void pContext; /* pContext from when function registered / int nParam; / Number of function parameters / sqlite3_rtree_dbl aParam; /* value of function parameters / void pUser; /* callback can use this, if desired / void (xDelUser)(void); / function to free pUser / sqlite3_rtree_dbl aCoord; /* Coordinates of node or entry to check / unsigned int anQueue; /* Number of pending entries in the queue / int nCoord; / Number of coordinates / int iLevel; / Level of current node or entry / int mxLevel; / The largest iLevel value in the tree / sqlite3_int64 iRowid; / Rowid for current entry / sqlite3_rtree_dbl rParentScore; / Score of parent node / int eParentWithin; / Visibility of parent node / int eWithin; / OUT: Visiblity / sqlite3_rtree_dbl rScore; / OUT: Write the score here / }; / ** Allowed values for sqlite3_rtree_query.eWithin and .eParentWithin. / #define NOT_WITHIN 0 / Object completely outside of query region / #define PARTLY_WITHIN 1 / Object partially overlaps query region / #define FULLY_WITHIN 2 / Object fully contained within query region / #ifdef __cplusplus } / end of the 'extern "C"' block / #endif #endif / ifndef _SQLITE3RTREE_H_ */	369.82 KB	2026-03-09 14:41

Terminal