日期:2013-05-04  浏览次数:20520 次

SQL Server里函数的两种用法(可以代替游标)

  1. 由于update里不能用存储过程,然而要依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:

以下是援用片段:
  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


  调用函数的存储过程部分

以下是援用片段:
  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. 我们要依据某表的某些记录,先计算后求和,由于无法存储两头值,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用。

  函数部分:

以下是援用片段:
  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


  调用函数的存储过程部分:

以下是援用片段:
  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


  函数还可以前往表等,希望大家一同讨论sqlserver里函数的妙用。