SQL Server 新增Delete操作回滾日誌方式
阿新 • • 發佈:2021-01-16
我們在操作表的時候難免會遇到誤刪除,或者刪掉的資料還想恢復的情況。
也許細心的朋友會用begin tran rollback/commit 這種事務來避免出現失誤,但這並不是最保險的。
如果提交了事物發現刪錯了或者忘記提交從而導致表被鎖,這些問題總是不可避免的。
廢話不多說了,下面直接進入正題,通過觸發器記錄刪除日誌,避免誤刪除帶來的尷尬。
下面這段sql粘過去直接執行,建立一個儲存過程:
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 --================================判斷是否存在 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) ) --=================================判斷是否存在 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,@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 --======================================判斷是否存在 DELETE 觸發器========================= 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; --==============================獲取GUID========================================== DECLARE @NEWID VARCHAR(36)=NEWID() --==============================將刪掉的資料插入備份表============================ INSERT INTO [dbo].[BACKUP_'+@TABLENAME+'] SELECT @NEWID,* FROM deleted --==============================記錄日誌和回滾操作的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 --非自增欄位 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
接著我們新建一張測試表,並且隨便往表中插入兩組資料:
Create table test ( id int,name varchar(10),msg varchar(10) ) Insert into test Select 1,'aa','hahah' Union all Select 2,'bb','heihei'
下面執行這個SP,在給test表添加回滾日誌:
EXEC SP_DELETE_LOG 'test'
細心的你不難發現,這時候資料庫裡面應該會多出兩張表:
然後我們刪掉一條資料:
DELETE FROM test WHERE id=1
再檢視那兩張表:
沒錯,這時候日誌表裡有資料了,然後我們把 UPDATE_LOG 表中的 RollBackSQ L這一列對應的值copy出來執行一下:
INSERT INTO test SELECT [id],[name],[msg] FROM BACKUP_test WHERE UPDATEGUID='B0CBBC4F-3432-4D4F-9E17-F17209BF6745'
別copy我上面這段sql,因為GUID肯定是不一樣的!
然而,資料恢復了:
最後,delete日誌的介紹就結束了,唯一的不滿足的是隻能作用在Delete 操作,其實UPDATE 操作也同樣需要這樣的回滾日誌。
以上為個人經驗,希望能給大家一個參考,也希望大家多多支援我們。如有錯誤或未考慮完全的地方,望不吝賜教。