SQL Server里函数的两种用法_中国IT运维网www.cnitom.com

1.因为update里不能用存储过程，然而要根据更新表的某些字段还要进行计算。我们常常采用游标的方法，这里用函数的方法实现。

函数部分：

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

调用函数的存储过程部分：

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.我们要根据某表的某些记录，先计算后求和，因为无法存储中间值，平时我们也用游标的方法进行计算。但sqlserver2000里支持：

SUM ( [ ALL | DISTINCT ] expression )

expression

是常量、列或函数，或者是算术、按位与字符串等运算符的任意组合。因此我们可以利用这一功能。

函数部分：

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

调用函数的存储过程部分：

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

函数还可以返回表等，希望大家一起讨论sqlserver里函数的妙用。