SQL Server 添加Delete操作回滚日志方式
我们在操作表的时候难免会遇到误删除,或者删掉的数据还想恢复的情况。
也许细心的朋友会用begin tran rollback/commit 这种事务来避免出现失误,但这并不是最保险的。
如果提交了事物发现删错了或者忘记提交从而导致表被锁,这些问题总是不可避免的。
废话不多说了,下面直接进入正题,通过触发器记录删除日志,避免误删除带来的尴尬。
下面这段sql粘过去直接运行,建立一个存储过程:
CREATE PROCEDURE [dbo].[SP_DELETE_LOG] @TABLENAME VARCHAR(50) AS BEGIN SET NOCOUNT ON; IF NOT EXISTS(SELECT * FROM sys.tables WHERE NAME = @TABLENAME AND TYPE = 'U' ) BEGIN PRINT'ERROR:not exist table '+@TABLENAME RETURN END IF (@TABLENAME LIKE'BACKUP_%' OR @TABLENAME='UPDATE_LOG' ) BEGIN --PRINT'ERROR:not exist table '+@TABLENAME RETURN END --================================判断是否存在 UPDATE_LOG 表============================ IF NOT EXISTS(SELECT * FROM sys.tables WHERE NAME = 'UPDATE_LOG' AND TYPE = 'U') CREATE TABLE UPDATE_LOG ( UpdateGUID VARCHAR(36), UpdateTime DATETIME, TableName varchar(20), UpdateType varchar(6), RollBackSQL varchar(1000) ) --=================================判断是否存在 BACKUP_ 表================================ IF NOT EXISTS(SELECT * FROM sys.tables WHERE NAME = 'BACKUP_'+@TABLENAME AND TYPE = 'U') BEGIN --DECLARE @SQL VARCHAR(500) --SET @SQL='SELECT TOP 1 NEWID() AS [UpdateGUID],* INTO BACKUP_'+@TABLENAME+' FROM '+ @TABLENAME+' -- DELETE FROM BACKUP_'+@TABLENAME --SELECT @SQL --EXEC(@SQL) DECLARE test_Cursor CURSOR FOR SELECT COLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.columns WHERE TABLE_NAME=@TABLENAME OPEN test_Cursor DECLARE @SQLTB NVARCHAR(MAX)='' DECLARE @COLUMN_NAME NVARCHAR(50),@DATA_TYPE VARCHAR(20),@CHARACTER_MAXIMUM_LENGTH INT FETCH NEXT FROM test_Cursor INTO @COLUMN_NAME,@DATA_TYPE,@CHARACTER_MAXIMUM_LENGTH WHILE @@FETCH_STATUS=0 BEGIN SET @SQLTB=@SQLTB+'['+@COLUMN_NAME+'] '+@DATA_TYPE+CASE ISNULL(@CHARACTER_MAXIMUM_LENGTH,0) WHEN 0 THEN '' WHEN -1 THEN '(MAX)' ELSE'('+CAST(@CHARACTER_MAXIMUM_LENGTH AS VARCHAR(10))+')' END+',' FETCH NEXT FROM test_Cursor INTO @COLUMN_NAME,@DATA_TYPE,@CHARACTER_MAXIMUM_LENGTH END SET @SQLTB='CREATE TABLE BACKUP_'+@TABLENAME+' (UpdateGUID varchar(36),'+SUBSTRING(@SQLTB,1,LEN(@SQLTB)-1)+')' EXEC (@SQLTB) CLOSE test_Cursor DEALLOCATE test_Cursor END --======================================判断是否存在 DELETE 触发器========================= IF NOT EXISTS(SELECT * FROM sys.objects WHERE NAME = 'tg_'+@TABLENAME+'_Delete' AND TYPE = 'TR') BEGIN DECLARE @SQLTR NVARCHAR(MAX) SET @SQLTR=' CREATE TRIGGER tg_'+@TABLENAME+'_Delete ON '+@TABLENAME+' AFTER delete AS BEGIN SET NOCOUNT ON; --==============================获取GUID========================================== DECLARE @NEWID VARCHAR(36)=NEWID() --==============================将删掉的数据插入备份表============================ INSERT INTO [dbo].[BACKUP_'+@TABLENAME+'] SELECT @NEWID,* FROM deleted --==============================记录日志和回滚操作的SQL=========================== --*********************生成列名********************** DECLARE @COLUMN NVARCHAR(MAX)='''' SELECT @COLUMN+='',[''+COLUMN_NAME+'']'' FROM INFORMATION_SCHEMA.columns WHERE TABLE_NAME='''+@TABLENAME+''' AND COLUMNPROPERTY(OBJECT_ID('''+@TABLENAME+'''),COLUMN_NAME,''IsIdentity'')<>1 --非自增字段 SET @COLUMN=SUBSTRING(@COLUMN,2,LEN(@COLUMN)) INSERT INTO [dbo].[UPDATE_LOG] SELECT @NEWID,GETDATE(),'''+@TABLENAME+''',''DELETE'',''INSERT INTO '+@TABLENAME+' SELECT ''+@COLUMN+'' FROM BACKUP_'+@TABLENAME+' WHERE UPDATEGUID=''''''+@NEWID+'''''''' END ' EXEC(@SQLTR) END END
接着我们新建一张测试表,并且随便往表中插入两组数据:
Create table test ( id int, name varchar(10), msg varchar(10) ) Insert into test Select 1,'aa','hahah' Union all Select 2,'bb','heihei'
下面执行这个SP,在给test表添加回滚日志:
EXEC SP_DELETE_LOG 'test'
细心的你不难发现,这时候数据库里面应该会多出两张表:
然后我们删掉一条数据:
DELETE FROM test WHERE id=1
再查看那两张表:
没错,这时候日志表里有数据了,然后我们把 UPDATE_LOG 表中的 RollBackSQ L这一列对应的值copy出来执行一下:
INSERT INTO test SELECT [id],[name],[msg] FROM BACKUP_test WHERE UPDATEGUID='B0CBBC4F-3432-4D4F-9E17-F17209BF6745'
别copy我上面这段sql,因为GUID肯定是不一样的!
然而,数据恢复了:
最后,delete日志的介绍就结束了,唯一的不满足的是只能作用在Delete 操作,其实UPDATE 操作也同样需要这样的回滚日志。
以上为个人经验,希望能给大家一个参考,也希望大家多多支持我们。如有错误或未考虑完全的地方,望不吝赐教。
赞 (0)