SQL Server里函數的兩種用法(可以代替游標)

1. 因為update里不能用存儲過程，然而要根據更新表的某些字段還要進行計算。我們常常采用游標的方法，這里用函數的方法實現。

函數部分：

以下是引用片段：CREATE FUNCTION [DBO].[FUN_GETTIME] (@TASKPHASEID INT) RETURNS FLOAT AS BEGIN DECLARE @TASKID INT, @HOUR FLOAT, @PERCENT FLOAT, @RETURN FLOAT IF @TASKPHASEID IS NULL BEGIN RETURN(0.0) END SELECT @TASKID=TASKID,@PERCENT=ISNULL(WORKPERCENT,0)/100 FROM TABLETASKPHASE WHERE ID=@TASKPHASEID SELECT @HOUR=ISNULL(TASKTIME,0) FROM TABLETASK WHERE ID=@TASKID SET @RETURN=@HOUR*@PERCENT RETURN (@RETURN) END

調用函數的存儲過程部分

以下是引用片段：CREATE PROCEDURE [DBO].[PROC_CALCCA] @ROID INT AS BEGIN DECLARE @CA FLOAT UPDATE TABLEFMECA SET Cvalue_M= ISNULL(MODERATE,0)*ISNULL(FMERATE,0)*ISNULL(B.BASFAILURERATE,0)*[DBO].[FUN_GETTIME](C.ID) FROM TABLEFMECA ,TABLERELATION B,TABLETASKPHASE C WHERE ROID=@ROID AND TASKPHASEID=C.ID AND B.ID=@ROID SELECT @CA=SUM(ISNULL(Cvalue_M,0)) FROM TABLEFMECA WHERE ROID=@ROID UPDATE TABLERELATION SET CRITICALITY=@CA WHERE ID=@ROID END GO

2. 我們要根據某表的某些記錄，先計算后求和，因為無法存儲中間值，平時我們也用游標的方法進行計算。但sqlserver2000里支持

SUM ( [ ALL | DISTINCT ] expression )

expression

是常量、列或函數，或者是算術、按位與字符串等運算符的任意組合。因此我們可以利用這一功能。

函數部分：

以下是引用片段：CREATE FUNCTION [DBO].[FUN_RATE] (@PARTID INT,@ENID INT,@SOURCEID INT, @QUALITYID INT,@COUNT INT) RETURNS FLOAT AS BEGIN DECLARE @QXS FLOAT, @G FLOAT, @RATE FLOAT IF (@ENID=NULL) OR (@PARTID=NULL) OR (@SOURCEID=NULL) OR (@QUALITYID=NULL) BEGIN RETURN(0.0) END SELECT @QXS= ISNULL(XS,0) FROM TABLEQUALITY WHERE ID=@QUALITYID SELECT @G=ISNULL(FRATE_G,0) FROM TABLEFAILURERATE WHERE (SUBKINDID=@PARTID) AND( ENID=@ENID) AND ( DATASOURCEID=@SOURCEID) AND( ( (ISNULL(MINCOUNT,0)<=ISNULL(@COUNT,0)) AND ( ISNULL(MAXCOUNT,0)>=ISNULL(@COUNT,0))) OR(ISNULL(@COUNT,0)>ISNULL(MAXCOUNT,0))) SET @RATE=ISNULL(@QXS*@G,0) RETURN (@RATE) END

調用函數的存儲過程部分：

以下是引用片段：CREATE PROC PROC_FAULTRATE @PARTID INTEGER, @QUALITYID INTEGER, @SOURCEID INTEGER, @COUNT INTEGER, @ROID INT, @GRADE INT,@RATE FLOAT=0 OUTPUTAS BEGIN DECLARE @TASKID INT SET @RATE=0.0 SELECT @TASKID=ISNULL(TASKPROID,-1) FROM TABLERELATION WHERE ID=(SELECT PID FROM TABLERELATION WHERE ID=@ROID) IF (@TASKID=-1) OR(@GRADE=1) BEGIN SET @RATE=0 RETURN END SELECT @RATE=SUM([DBO].[FUN_RATE] (@PARTID,ENID,@SOURCEID, @QUALITYID,@COUNT) *ISNULL(WORKPERCENT,0)/100.0) FROM TABLETASKPHASE WHERE TASKID=@TASKID END GO

函數還可以返回表等，希望大家一起討論sqlserver里函數的妙用。