my_bool mysql_rollback(MYSQL *mysql)
Rolls back the current transaction.
The action of this function is subject to the value of the
variable. In particular, if the value of
completion_type is 2, the
server performs a release after terminating a transaction and
closes the client connection. The client program should call
mysql_close() to close the
connection from the client side.
Zero for success. Nonzero if an error occurred.