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SQLITE3_VTAB_NOCHANGE(3)   Library Functions Manual   SQLITE3_VTAB_NOCHANGE(3)

NAME
     sqlite3_vtab_nochange - Determine If Virtual Table Column Access Is For
     UPDATE

SYNOPSIS
     int
     sqlite3_vtab_nochange(sqlite3_context*);

DESCRIPTION
     If the sqlite3_vtab_nochange(X) routine is called within the xColumn
     method of a virtual table, then it returns true if and only if the column
     is being fetched as part of an UPDATE operation during which the column
     value will not change.  Applications might use this to substitute a
     return value that is less expensive to compute and that the corresponding
     xUpdate method understands as a "no-change" value.

     If the xColumn method calls sqlite3_vtab_nochange() and finds that the
     column is not changed by the UPDATE statement, then the xColumn method
     can optionally return without setting a result, without calling any of
     the sqlite3_result_xxxxx() interfaces.  In that case,
     sqlite3_value_nochange(X) will return true for the same column in the
     xUpdate method.

SEE ALSO
     sqlite3_result_blob(3)

NetBSD 9.99                    December 19, 2018                   NetBSD 9.99