本文主要主要讲解了SQL Server数据库中函数的两种用法，具体内容请参考下文：
◆1. 由于update里不能用存储过程，并且由于根据更新表的某些字段还要进行计算。所以很多人采用的是游标的方法，在这里我们可以用函数的方法实现。
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SQL Server 2000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
