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Command: sqlite3_stmt_readonly | Section: 3 | Source: NetBSD | File: sqlite3_stmt_readonly.3
SQLITE3_STMT_READONLY(3) FreeBSD Library Functions Manual
NAME
sqlite3_stmt_readonly - Determine If An SQL Statement Writes The Database
SYNOPSIS
int
sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
DESCRIPTION
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:
SELECT eval('DELETE FROM t1') FROM t2;
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. The
sqlite3_stmt_readonly() interface returns true for BEGIN since BEGIN
merely sets internal flags, but the BEGIN IMMEDIATE and BEGIN EXCLUSIVE
commands do touch the database and so sqlite3_stmt_readonly() returns
false for those commands.
SEE ALSO
sqlite3_create_function(3), sqlite3_stmt(3), sqlite3_exec(3)
FreeBSD 14.1-RELEASE-p8 December 19, 2018 FreeBSD 14.1-RELEASE-p8