[cubrid_close|http://www.php.net/manual/en/function.cubrid-close.php] is a MySQL compatible function and the resource parameter is optional. The function of [cubrid_disconnect|http://www.php.net/manual/en/function.cubrid-disconnect.php] is same with [cubrid_close|http://www.php.net/manual/en/function.cubrid-close.php], so does the parameter of [cubrid_disconnect|http://www.php.net/manual/en/function.cubrid-disconnect.php].