如果我们拥有ALTER ROUTINE特权,那么我们可以借助ALTER FUNCTION查询更改MySQL存储功能。它的语法如下-
ALTER FUNCTION function_name [characteristic ...] characteristic: { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA } | SQL SECURITY { DEFINER | INVOKER } | COMMENT 'string'
在这里,function_name是我们要更改的函数的名称。
ALTER FUNCTION语句可以更改上面在语法中定义的存储函数的特征。我们可以在ALTER FUNCTION语句中指定多个更改。但是我们不能使用此语句更改参数或函数主体。为了说明这一点,我们在以下示例中在函数名称“ factorial”中添加注释-
mysql> ALTER FUNCTION factorial COMMENT 'Can accept fraction values'; mysql> Show Create Function factorial\G *************************** 1. row *************************** Function: factorial sql_mode: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION Create Function: CREATE DEFINER=`root`@`localhost` FUNCTION `factorial`(n DECIMAL(3,0)) RETURNS decimal(20,0) DETERMINISTIC COMMENT 'Can accept fraction values' BEGIN DECLARE factorial DECIMAL(20,0) DEFAULT 1; DECLARE counter DECIMAL(3,0); SET counter = n; factorial_loop: REPEAT SET factorial = factorial * counter; SET counter = counter - 1; UNTIL counter = 1 END REPEAT; RETURN factorial; END character_set_client: cp850 collation_connection: cp850_general_ci Database Collation: latin1_swedish_ci 1 row in set (0.00 sec)
从CREAT FUNCTION查询中,很明显,注释已添加到函数“阶乘”的定义中。