這篇文章主要介紹了MySQL觸發(fā)器運(yùn)用于遷移和同步數(shù)據(jù)的實(shí)例教程,分別是SQL Server數(shù)據(jù)遷移至MySQL以及同步備份數(shù)據(jù)表記錄的兩個(gè)例子,需要的朋友可以參考下

1.遷移數(shù)據(jù)進(jìn)行數(shù)據(jù)庫移植，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

簡單了解了下MySQL中，Trigger的語法。

# 創(chuàng)建

CREATE TRIGGER

{ BEFORE | AFTER }

{ INSERT | UPDATE | DELETE }

ON

FOR EACH ROW

# 刪除

DROP TRIGGER

注：創(chuàng)建觸發(fā)器需要CREATE TRIGGER權(quán)限。(HeidiSQL中執(zhí)行Trigger語句會有bug)

由于MySQL中的每個(gè)觸發(fā)器只能針對一個(gè)動作，所以本次移植就需要創(chuàng)建兩個(gè)觸發(fā)器。對于發(fā)生變更的行，在觸發(fā)器中可以用 NEW 來代替。

下邊的觸發(fā)器有什么問題嗎？

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 ;

問題就是，沒有考慮到觸發(fā)器中的修改也會觸發(fā)觸發(fā)器，進(jìn)入了死循環(huán)。做了如下修改后，終于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.同步備份數(shù)據(jù)記錄表添加記錄到新記錄表

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觸發(fā)器監(jiān)控mysql數(shù)據(jù)表記錄刪除操作 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 ;

刪除前 添加原記錄備份到另一記錄表

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 ;

總結(jié)

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