sqlite3.h

sqllive C开发的轻量级的数据库。 对想深入了解数据库的数据结构有很好的借鉴

/*
** CAPI3REF: Count The Number Of Rows Modified {F12240}
**
** This function returns the number of database rows that were changed
** or inserted or deleted by the most recently completed SQL statement
** on the connection specified by the first parameter.  Only
** changes that are directly specified by the INSERT, UPDATE, or
** DELETE statement are counted.  Auxiliary changes caused by
** triggers are not counted. Use the [sqlite3_total_changes()] function
** to find the total number of changes including changes caused by triggers.
**
** A "row change" is a change to a single row of a single table
** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
** are changed as side effects of REPLACE constraint resolution,
** rollback, ABORT processing, DROP TABLE, or by any other
** mechanisms do not count as direct row changes.
**
** A "trigger context" is a scope of execution that begins and
** ends with the script of a trigger.  Most SQL statements are
** evaluated outside of any trigger.  This is the "top level"
** trigger context.  If a trigger fires from the top level, a
** new trigger context is entered for the duration of that one
** trigger.  Subtriggers create subcontexts for their duration.
**
** Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
** not create a new trigger context.
**
** This function returns the number of direct row changes in the
** most recent INSERT, UPDATE, or DELETE statement within the same
** trigger context.
**
** So when called from the top level, this function returns the
** number of changes in the most recent INSERT, UPDATE, or DELETE
** that also occurred at the top level.
** Within the body of a trigger, the sqlite3_changes() interface
** can be called to find the number of
** changes in the most recently completed INSERT, UPDATE, or DELETE
** statement within the body of the same trigger.
** However, the number returned does not include in changes
** caused by subtriggers since they have their own context.
**
** SQLite implements the command "DELETE FROM table" without
** a WHERE clause by dropping and recreating the table.  (This is much
** faster than going through and deleting individual elements from the
** table.)  Because of this optimization, the deletions in
** "DELETE FROM table" are not row changes and will not be counted
** by the sqlite3_changes() or [sqlite3_total_changes()] functions.
** To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.
**
** INVARIANTS:
**
** {F12241} The [sqlite3_changes()] function returns the number of
**          row changes caused by the most recent INSERT, UPDATE,
**          or DELETE statement on the same database connection and
**          within the same trigger context, or zero if there have
**          not been any qualifying row changes.
**
** LIMITATIONS:
**
** {U12252} If a separate thread makes changes on the same database connection
**          while [sqlite3_changes()] is running then the value returned
**          is unpredictable and unmeaningful.
*/
int sqlite3_changes(sqlite3*);

/*
** CAPI3REF: Total Number Of Rows Modified {F12260}
***
** This function returns the number of row changes caused
** by INSERT, UPDATE or DELETE statements since the database handle
** was opened.  The count includes all changes from all trigger
** contexts.  But the count does not include changes used to
** implement REPLACE constraints, do rollbacks or ABORT processing,
** or DROP table processing.
** The changes
** are counted as soon as the statement that makes them is completed 
** (when the statement handle is passed to [sqlite3_reset()] or 
** [sqlite3_finalize()]).
**
** SQLite implements the command "DELETE FROM table" without
** a WHERE clause by dropping and recreating the table.  (This is much
** faster than going
** through and deleting individual elements from the table.)  Because of
** this optimization, the change count for "DELETE FROM table" will be
** zero regardless of the number of elements that were originally in the
** table. To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.
**
** See also the [sqlite3_changes()] interface.
**
** INVARIANTS:
** 
** {F12261} The [sqlite3_total_changes()] returns the total number
**          of row changes caused by INSERT, UPDATE, and/or DELETE
**          statements on the same [database connection], in any
**          trigger context, since the database connection was
**          created.
**
** LIMITATIONS:
**
** {U12264} If a separate thread makes changes on the same database connection
**          while [sqlite3_total_changes()] is running then the value 
**          returned is unpredictable and unmeaningful.
*/
int sqlite3_total_changes(sqlite3*);

/*
** CAPI3REF: Interrupt A Long-Running Query {F12270}
**
** 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 is very nearly finished at the time when sqlite3_interrupt()
** is called, then it might not have an opportunity to be interrupted.
** It 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.
** A call to sqlite3_interrupt() has no effect on SQL statements
** that are started after sqlite3_interrupt() returns.
**
** INVARIANTS:
**
** {F12271} The [sqlite3_interrupt()] interface will force all running
**          SQL statements associated with the same database connection
**          to halt after processing at most one additional row of
**          data.
**
** {F12272} Any SQL statement that is interrupted by [sqlite3_interrupt()]
**          will return [SQLITE_INTERRUPT].
**
** LIMITATIONS:
**
** {U12279} If the database connection closes while [sqlite3_interrupt()]
**          is running then bad things will likely happen.
*/
void sqlite3_interrupt(sqlite3*);

/*
** CAPI3REF: Determine If An SQL Statement Is Complete {F10510}
**
** These routines are useful for command-line input to determine if the
** currently entered text seems to form complete a SQL statement or
** if additional input is needed before sending the text into
** SQLite for parsing.  These routines return true 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 fragment of a
** 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.
**
** These routines do not parse the SQL and
** so will not detect syntactically incorrect SQL.
**
** INVARIANTS:
**
** {F10511} The sqlite3_complete() and sqlite3_complete16() functions
**          return true (non-zero) if and only if the last
**          non-whitespace token in their input is a semicolon that
**          is not in between the BEGIN and END of a CREATE TRIGGER
**          statement.
**
** LIMITATIONS:
**
** {U10512} The input to sqlite3_complete() must be a zero-terminated
**          UTF-8 string.
**
** {U10513} The input to sqlite3_complete16() must be a zero-terminated
**          UTF-16 string in native byte order.
*/
int sqlite3_complete(const char *sql);
int sqlite3_complete16(const void *sql);

/*
** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors {F12310}
**
** This routine identifies a callback function that might be
** invoked whenever an attempt is made to open a database table 
** that another thread or process has locked.
** If the busy callback is NULL, then [SQLITE_BUSY]
** or [SQLITE_IOERR_BLOCKED]
** is returned immediately upon encountering the lock.
** If the busy callback is not NULL, then the
** callback will be invoked with two arguments.  The
** first argument to the handler is a copy of the void* pointer which
** is the third argument to this routine.  The second argument to
** the handler is the number of times that the busy handler has
** been invoked for this locking event.   If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
** If the callback returns non-zero, then another attempt
** is made to open the database for reading 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] or
** [SQLITE_IOERR_BLOCKED] 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.
**
** The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
** when SQLite is in the middle of a large transaction where all the
** changes will not fit into the in-memory cache.  SQLite will
** already hold a RESERVED lock on the database file, but it needs
** to promote this lock to EXCLUSIVE so that it can spill cache
** pages into the database file without harm to concurrent
** readers.  If it is unable to promote the lock, then the in-memory
** cache will be left in an inconsistent state and so the error
** code is promoted from the relatively benign [SQLITE_BUSY] to
** the more severe [SQLITE_IOERR_BLOCKED].  This error code promotion
** forces an automatic rollback of the changes.  See the
** <a href="http://www.sqlite.org/cvstrac/wiki?p=CorruptionFollowingBusyError">
** CorruptionFollowingBusyError</a> wiki page for a discussion of why
** this is important.
**	
** There can only be a single busy handler defined for each database
** connection.  Setting a new busy handler clears any previous one. 
** Note that calling [sqlite3_busy_timeout()] will also set or clear
** the busy handler.
**
** INVARIANTS:
**
** {F12311} The [sqlite3_busy_handler()] function replaces the busy handler
**          callback in the database connection identified by the 1st
**          parameter with a new busy handler identified by the 2nd and 3rd
**          parameters.
**
** {F12312} The default busy handler for new database connections is NULL.
**
** {F12314} When two or more database connection share a common cache,
**          the busy handler for the database connection currently using
**          the cache is invoked when the cache encounters a lock.
**
** {F12316} If a busy handler callback returns zero, then the SQLite
**          interface that provoked the locking event will return
**          [SQLITE_BUSY].
**
** {F12318} SQLite will invokes the busy handler with two argument which
**          are a copy of the pointer supplied by the 3rd parameter to
**          [sqlite3_busy_handler()] and a count of the number of prior
**          invocations of the busy handler for the same locking event.
**
** LIMITATIONS:
**
** {U12319} A busy handler should not call close the database connection
**          or prepared statement that invoked the busy handler.
*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout {F12340}
**
** This routine sets a [sqlite3_busy_handler | busy handler]
** that sleeps for a while when a
** table is locked.  The handler will sleep multiple times until 
** at least "ms" milliseconds of sleeping have been done. {F12343} After
** "ms" milliseconds of sleeping, the handler returns 0 which
** causes [sqlite3_step()] to return [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
**
** 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.  If another busy handler was defined  
** (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.
**
** INVARIANTS:
**
** {F12341} The [sqlite3_busy_timeout()] function overrides any prior
**          [sqlite3_busy_timeout()] or [sqlite3_busy_handler()] setting
**          on the same database connection.
**
** {F12343} If the 2nd parameter to [sqlite3_busy_timeout()] is less than
**          or equal to zero, then the busy handler is cleared so that
**          all subsequent locking events immediately return [SQLITE_BUSY].
**
** {F12344} If the 2nd parameter to [sqlite3_busy_timeout()] is a positive
**          number N, then a busy handler is set that repeatedly calls