分析SQL Server里函数的两种用法-控件新闻-慧都网

分析SQL Server里函数的两种用法

原创|其它|编辑：郝浩|2009-06-09 17:53:36.000|阅读 375 次

概述：

本文介绍了SQL Server里函数的两种用法，它可以代替游标，供大家参考！

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