本文实例讲述了mysql 触发器语法与应用。分享给大家供大家参考,具体如下:
例子:创建触发器,记录表的增、删、改操作记录
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//创建 user 表;
DROP TABLE IF EXISTS ` user `;
CREATE TABLE ` user ` (
`id` bigint (20) NOT NULL AUTO_INCREMENT,
`account` varchar (255) DEFAULT NULL ,
` name ` varchar (255) DEFAULT NULL ,
`address` varchar (255) DEFAULT NULL ,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
//创建对 user 表操作历史表
DROP TABLE IF EXISTS `user_history`;
CREATE TABLE `user_history` (
`id` bigint (20) NOT NULL AUTO_INCREMENT,
`user_id` bigint (20) NOT NULL ,
`operatetype` varchar (200) NOT NULL ,
`operatetime` datetime NOT NULL ,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
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DELIMITER:改变输入的结束符,默认情况下输入结束符是分号;,这里把它改成了两个分号;;,这样做的目的是把多条含分号的语句做个封装,全部输入完之后一起执行,而不是一遇到默认的分号结束符就自动执行;
- new:当触发插入和更新事件时可用,指向的是被操作的记录
- old: 当触发删除和更新事件时可用,指向的是被操作的记录
INSERT:
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DROP TRIGGER IF EXISTS `tri_insert_user`;
DELIMITER ;;
CREATE TRIGGER `tri_insert_user` AFTER INSERT ON ` user ` FOR EACH ROW begin
INSERT INTO user_history(user_id, operatetype, operatetime) VALUES (new.id, 'add a user' , now());
end
;;
DELIMITER ;
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UPDATE:
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DROP TRIGGER IF EXISTS `tri_update_user`;
DELIMITER ;;
CREATE TRIGGER `tri_update_user` AFTER UPDATE ON ` user ` FOR EACH ROW begin
INSERT INTO user_history(user_id,operatetype, operatetime) VALUES (new.id, 'update a user' , now());
end
;;
DELIMITER ;
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DELETE:
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DROP TRIGGER IF EXISTS `tri_delete_user`;
DELIMITER ;;
CREATE TRIGGER `tri_delete_user` AFTER DELETE ON ` user ` FOR EACH ROW begin
INSERT INTO user_history(user_id, operatetype, operatetime) VALUES (old.id, 'delete a user' , now());
end
;;
DELIMITER ;
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希望本文所述对大家MySQL数据库计有所帮助。
原文链接:https://blog.csdn.net/qq_42176520/article/details/103904032