这篇文章主要介绍了MySQL触发器运用于迁移和同步数据的实例教程,分别是SQL Server数据迁移至MySQL以及同步备份数据表记录的两个例子,需要的朋友可以参考下

1.迁移数据进行数据库移植，SQL Server=>MySQL。SQL Server上有如下的Trigger

SET QUOTED_IDENTIFIER ON

GO

SET ANSI_NULLS ON

GO

ALTER TRIGGER [trg_risks] ON dbo.projectrisk

FOR INSERT, UPDATE

AS

BEGIN

UPDATE projectrisk

SET classification =

case

when calc>= 9 then 3

when calc <9 and calc>=4 then 2

when calc <4 then 1

end

from (select inserted.id, inserted.possibility*inserted.severity as calc from inserted) as T1

where projectrisk.id = T1.id

END

GO

SET QUOTED_IDENTIFIER OFF

GO

SET ANSI_NULLS ON

GO

简单了解了下MySQL中，Trigger的语法。

# 创建

CREATE TRIGGER

{ BEFORE | AFTER }

{ INSERT | UPDATE | DELETE }

ON

FOR EACH ROW

# 删除

DROP TRIGGER

注：创建触发器需要CREATE TRIGGER权限。(HeidiSQL中执行Trigger语句会有bug)

由于MySQL中的每个触发器只能针对一个动作，所以本次移植就需要创建两个触发器。对于发生变更的行，在触发器中可以用 NEW 来代替。

下边的触发器有什么问题吗？

delimiter &&

CREATE TRIGGER trg_risks_insert

AFTER INSERT ON `projectrisk`

FOR EACH ROW

UPDATE projectrisk SET classification = CASE

WHEN possibility*severity>=9 THEN 3

WHEN possibility*severity <9 AND possibility*severity>=4 THEN 2

WHEN possibility*severity <4 THEN 1

END

WHERE id = new.id;

&&

CREATE TRIGGER trg_risks_update

AFTER UPDATE ON `projectrisk`

FOR EACH ROW

UPDATE projectrisk SET classification = CASE

WHEN possibility*severity>=9 THEN 3

WHEN possibility*severity <9 AND possibility*severity>=4 THEN 2

WHEN possibility*severity <4 THEN 1

END

WHERE id = new.id;

&&

delimiter ;

问题就是，没有考虑到触发器中的修改也会触发触发器，进入了死循环。做了如下修改后，终于OK了。

delimiter &&

CREATE TRIGGER trg_risks_insert

BEFORE INSERT ON `projectrisk`

FOR EACH ROW

BEGIN

SET new.classification = CASE

WHEN new.possibility*new.severity>=9 THEN 3

WHEN new.possibility*new.severity <9 AND new.possibility*new.severity>=4 THEN 2

WHEN new.possibility*new.severity <4 THEN 1

END;

END

&&

CREATE TRIGGER trg_risks_update

BEFORE UPDATE ON `projectrisk`

FOR EACH ROW

BEGIN

SET new.classification = CASE

WHEN new.possibility*new.severity>=9 THEN 3

WHEN new.possibility*new.severity <9 AND new.possibility*new.severity>=4 THEN 2

WHEN new.possibility*new.severity <4 THEN 1

END;

END

&&

delimiter ;

2.同步备份数据记录表添加记录到新记录表

DELIMITER $$

USE `DB_Test`$$

CREATE

/*!50017 DEFINER = 'root'@'%' */

TRIGGER `InsertOPM_Alarm_trigger` BEFORE INSERT ON `OPM_Alarm`

FOR EACH ROW BEGIN

INSERT INTO OPM_Alarm_copy (AlarmId,AlarmCode,AlarmTypeId,AlarmLevelId,AlarmObjectCode,AlarmStatus,AlarmHandleUser,

AlarmHandleTime,ADDTIME,ParkUserId,BerthCode,BargainOrderCode,BerthStartTime)

VALUES(new.AlarmId,new.AlarmCode,new.AlarmTypeId,new.AlarmLevelId,new.AlarmObjectCode,new.AlarmStatus,new.AlarmHandleUser,

new.AlarmHandleTime,new.ADDTIME,new.ParkUserId,new.BerthCode,new.BargainOrderCode,new.BerthStartTime);

END;

$$

DELIMITER ;

CREATE TRIGGER InsertOPM_Alarm_trigger

BEFORE INSERT ON OPM_Alarm

FOR EACH ROW

BEGIN

INSERT INTO OPM_Alarm_copy (AlarmId,AlarmCode,AlarmTypeId,AlarmLevelId,AlarmObjectCode,AlarmStatus,AlarmHandleUser,

AlarmHandleTime,ADDTIME,ParkUserId,BerthCode,BargainOrderCode,BerthStartTime)

VALUES(new.AlarmId,new.AlarmCode,new.AlarmTypeId,new.AlarmLevelId,new.AlarmObjectCode,new.AlarmStatus,new.AlarmHandleUser,

new.AlarmHandleTime,new.ADDTIME,new.ParkUserId,new.BerthCode,new.BargainOrderCode,new.BerthStartTime);

END ;

mysql触发器监控mysql数据表记录删除操作 DELIMITER $$

USE `DB_Test`$$

DROP TRIGGER /*!50032 IF EXISTS */ `SYS_OPM_trigger`$$

CREATE

/*!50017 DEFINER = 'root'@'%' */

TRIGGER `SYS_OPM_trigger` AFTER DELETE ON `OPM_Alarm`

FOR EACH ROW BEGIN

DECLARE str VARCHAR(40000);

SET str=CONCAT(old.AlarmId,'@',old.AlarmCode,'@',old.AlarmTypeId,'@',old.AlarmLevelId,'@',

old.AlarmObjectCode,'@',old.AlarmStatus,'@',old.AlarmHandleUser,'@',old.AlarmHandleTime,'@',

old.AddTime,'@',old.ParkUserId,'@',old.BerthCode,'@',old.BargainOrderCode,'@',old.BerthStartTime);

INSERT INTO OPM_AlarmAction_log(UserName,Client_IP,Delete_before_key,Delete_Date)

VALUES(SUBSTRING_INDEX(USER(),'@',1),SUBSTRING_INDEX(USER(),'@',-1), str, NOW());

END;

$$

DELIMITER ;

删除前 添加原记录备份到另一记录表

DELIMITER $$

USE `DB_Test`$$

DROP TRIGGER /*!50032 IF EXISTS */ `InsertOPM_Alarm_trigger`$$

CREATE

/*!50017 DEFINER = 'root'@'%' */

TRIGGER `InsertOPM_Alarm_trigger` BEFORE

DELETE ON `OPM_Alarm`

FOR EACH ROW BEGIN

INSERT INTO OPM_Alarm_copy

(AlarmId,AlarmCode,AlarmTypeId,AlarmLevelId,AlarmObjectCode,AlarmStatus,AlarmHandleUser,

AlarmHandleTime,ADDTIME,ParkUserId,BerthCode,BargainOrderCode,BerthStartTime)

VALUES

(old.AlarmId,old.AlarmCode,old.AlarmTypeId,old.AlarmLevelId,old.AlarmObjectCode,old.AlarmS

tatus,old.AlarmHandleUser,

old.AlarmHandleTime,old.ADDTIME,old.ParkUserId,old.BerthCode,old.BargainOrderCode,old.Bert

hStartTime);

END;

$$

DELIMITER ;