In the DB Access Module for MySQL, the database callbacks
preEnvAllocate() and
postEnvAllocate() are invoked during the construction of the
RWDBDatabase object. The callback
preEnvDestroy() is invoked while destroying the
RWDBDatabase object. The connection callbacks are invoked with respect to the allocation, deallocation, connect and disconnect of the MySQL connection structure.
The DB Access Module for MySQL disconnects and deallocates the connection structure in a single vendor call
mysql_close(). Hence both callbacks
preDisconnect() and
preConnDestroy() are invoked before the call to
mysql_close(). Please refer to the
DB Interface Module User's Guide for more information.