php - Mysql 触发器 IF 目标字段已更改

Question

我想仅在某些字段被修改时才触发 UPDATE 触发器。是否可以用 if 语句来做？执行特定查询。

示例(未按所示工作):

DROP TRIGGER IF EXISTS `catch_mytable_update`//
CREATE TRIGGER `catch_mytable_update` AFTER UPDATE ON `mytable`
 FOR EACH ROW BEGIN

IF (old.name != new.name) THEN

DELETE FROM trigger WHERE tablename='mytable' AND rowid = new.id;
INSERT INTO trigger (tablename, rowid, cmd, cmduser, time) VALUES('mytable', new.id, 'UPDATE', CURRENT_USER(), NOW());

ENDIF//

END//

分隔符://

Answer 1

尝试改变:

    IF (name.old != name.new) THEN

至:

    IF old.name != new.name THEN