SQL Server添加Delete操作回滚日志

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)ASBEGINSET NOCOUNT ON;    IF NOT EXISTS(SELECT * FROM sys.tables WHERE NAME = @TABLENAME AND TYPE = 'U' )BEGINPRINT'ERROR：not exist table '+@TABLENAMERETURNENDIF (@TABLENAME LIKE'BACKUP_%' OR @TABLENAME='UPDATE_LOG' )BEGIN--PRINT'ERROR：not exist table '+@TABLENAMERETURNEND--================================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 FORSELECT COLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.columns WHERE TABLE_NAME=@TABLENAMEOPEN test_CursorDECLARE @SQLTB NVARCHAR(MAX)=''DECLARE @COLUMN_NAME NVARCHAR(50),@DATA_TYPE VARCHAR(20),@CHARACTER_MAXIMUM_LENGTH INTFETCH NEXT FROM test_Cursor INTO @COLUMN_NAME,@DATA_TYPE,@CHARACTER_MAXIMUM_LENGTHWHILE @@FETCH_STATUS=0BEGINSET @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_LENGTHENDSET @SQLTB='CREATE TABLE BACKUP_'+@TABLENAME+' (UpdateGUID varchar(36),'+SUBSTRING(@SQLTB,1,LEN(@SQLTB)-1)+')'EXEC (@SQLTB)CLOSE test_Cursor DEALLOCATE test_CursorEND--======================================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')BEGINDECLARE @SQLTR NVARCHAR(MAX)SET @SQLTR='CREATE TRIGGER tg_'+@TABLENAME+'_DeleteON  '+@TABLENAME+'AFTER deleteAS BEGINSET 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.columnsWHERE 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)ENDEND

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。

今天就到这里结束了，下一篇我会介绍关于UPDATE的回滚日志的建立。Bye Bye~~~