游標的的使用有日常的開發和維護的過程不使用的並不多，但是碰到一些棘手的問題的時候，游標時常是個非常好的幫手，下面就說下游標的使用方法，方法自己以后查閱，和加深一些印象，下面以一個存儲過程為例
T-SQL中的游標定義在MSDN中如下: DECLARE cursor_name CURSOR [ LOCAL | GLOBAL ] [ FORWARD_ONLY | SCROLL ] [ STATIC | KEYSET | DYNAMIC | FAST_FORWARD ] [ READ_ONLY | SCROLL_LOCKS | OPTIMISTIC ] [ TYPE_WARNING ] FOR select_statement [ FOR UPDATE [ OF column_name [ ,...n ] ] ] [;]
ALTER PROCEDURE [dbo]. [XXXX] @ProcessName NVARCHAR (20) ---流程名 AS DECLARE @tempIncident INT DECLARE @tempCode NVARCHAR( 20) DECLARE @incident NVARCHAR( 100) ---實例號 DECLARE @bicode NVARCHAR( 200)--- 單號 DECLARE @taskCnt INT ---task為的數量 DECLARE @flag INT DECLARE @bflag INT SET @flag = 0 SET @bflag = 0 ----定義一個游標-- ----定義游標和定義一個變量是差不多的，不過后面要指定一個的查詢語句， DECLARE mycur CURSOR FOR ( SELECT bic. BI_Code ,----這時兩個的數據是要使用的數據 bic.BI_Incident FROM xxxxx AS inc , bic AS bic WHERE inc .PROCESSNAME = bic .BI_ProcessName AND INCIDENT = bic.BI_Incident AND PROCESSNAME = @ProcessName AND inc .STATUS = 2 AND ( bic. BI_AuditState = 4010 OR bic .BI_AuditState = 4040 ) ) OPEN mycur--打開這個游標 FETCH NEXT FROM mycur INTO @tempCode, @tempIncident ---把值放到變量中 --循環這個值 --這是一個系統的取游標值的一個變量 WHILE @@FETCH_STATUS = 0 BEGIN SELECT @taskCnt = COUNT(*) FROM xxxxx WHERE INCIDENT = @tempIncident AND PROCESSNAME = @ProcessName AND STATUS = 1 IF @taskCnt > 0 ---有task=1 的數據則是可以自動處理的 BEGIN IF @flag = 0 BEGIN SET @incident = CAST(@tempIncident AS NVARCHAR) END ELSE SET @incident = @incident + ',' + CAST (@tempIncident AS NVARCHAR ) SET @flag = 1 END ELSE BEGIN IF @bflag = 0 SET @bicode = @tempCode ELSE SET @bicode = @bicode + ',' + @tempCode SET @bflag = 1 END ---這里的是把數據再次放到變量里面，以便循環的使用 FETCH NEXT FROM mycur INTO @tempCode, @tempIncident END CLOSE mycur DEALLOCATE mycur IF @bicode IS NULL SET @bicode = 'NULL' IF @incident IS NULL SET @incident = 'NULL' ELSE UPDATE xxxxx SET STATUS = 1 WHERE PROCESSNAME = @ProcessName AND INCIDENT IN ( SELECT value FROM dbo .fn_Split( @incident, ',') )
SQL 函數的使用：
函數在SQL中的使用提高了SQL代碼的重復利用，也方便我們更高效的去用SQL做更多的事：下面我就對標量的函數進行說明，其它的東西也基本上是大同小異.
1、標量函數 Create function 函數名（參數） Returns 返回值數據類型 [with {Encryption | Schemabinding }] [as] begin SQL語句(必須有return 變量或值)
例如：
ALTER FUNCTION [dbo]. [fn_Split](@sText varchar( 8000), @sDelim varchar(20 ) = ' ') RETURNS @retArray TABLE (idx smallint Primary Key, value varchar(8000 ) COLLATE SQL_Latin1_General_CP1_CI_AS )
這樣就是把一個函數的基本形式定義好了 如同在代碼中寫出 public string get(){}
后面的代碼也就是日常的sql查詢或者是一些的特殊的處理
ALTER FUNCTION [dbo]. [fn_Split](@sText varchar( 8000), @sDelim varchar(20 ) = ' ') RETURNS @retArray TABLE (idx smallint Primary Key, value varchar(8000 ) COLLATE SQL_Latin1_General_CP1_CI_AS ) AS BEGIN DECLARE @idx smallint , @value varchar(8000 ), @bcontinue bit, @iStrike smallint, @iDelimlength tinyint IF @sDelim = 'Space' BEGIN SET @sDelim = ' ' END SET @idx = 0 SET @sText = LTrim(RTrim (@sText)) SET @iDelimlength = DATALENGTH(@sDelim ) SET @bcontinue = 1 IF NOT ((@iDelimlength = 0 ) or (@sDelim = 'Empty')) BEGIN WHILE @bcontinue = 1 BEGIN --If you can find the delimiter in the text, retrieve the first element and --insert it with its index into the return table. IF CHARINDEX (@sDelim, @sText)> 0 BEGIN SET @value = SUBSTRING(@sText ,1, CHARINDEX( @sDelim,@sText )-1) BEGIN INSERT @retArray (idx , value ) VALUES (@idx , @value ) END --Trim the element and its delimiter from the front of the string. --Increment the index and loop. SET @iStrike = DATALENGTH(@value ) + @iDelimlength SET @idx = @idx + 1 SET @sText = LTrim(Right(@sText ,DATALENGTH( @sText) - @iStrike )) END ELSE BEGIN --If you can’t find the delimiter in the text, @sText is the last value in --@retArray. SET @value = @sText BEGIN INSERT @retArray (idx , value ) VALUES (@idx , @value ) END --Exit the WHILE loop. SET @bcontinue = 0 END END END ELSE BEGIN WHILE @bcontinue=1 BEGIN --If the delimiter is an empty string, check for remaining text --instead of a delimiter. Insert the first character into the --retArray table. Trim the character from the front of the string. --Increment the index and loop. IF DATALENGTH(@sText )>1 BEGIN SET @value = SUBSTRING(@sText ,1, 1) BEGIN INSERT @retArray (idx , value ) VALUES (@idx , @value ) END SET @idx = @idx+1 SET @sText = SUBSTRING(@sText ,2, DATALENGTH(@sText )-1) END ELSE BEGIN --One character remains. --Insert the character, and exit the WHILE loop. INSERT @retArray (idx , value ) VALUES (@idx , @sText ) SET @bcontinue = 0 END END END RETURN END