计算指定年月的最后一天的自定义函数

/*

    Name :    Fun_YiYueDeZuiHouYiTian

    Function :   根据传入的格式如“200311”的年月值计算出当月的最后一天

    Parameters :   

                        BenYue  本月

                            Type :  Char(6)  

                            Format :  "200311"

    ReturnValue :   

                        格式如“200310”的年月值

                            Type :  Char(6)

    Steps :

    Author :   Waxdoll Cheung

    Date :    2004-04-04

*/

CREATE FUNCTION dbo.Fun_YiYueDeZuiHouYiTian

 (

  @BenYue CHAR(6)

 )

RETURNS CHAR(10)

AS

 BEGIN

  DECLARE @ReturnValue CHAR(2)

  DECLARE @YueFen CHAR(2)

  DECLARE @NianFen CHAR(4)

  SET @YueFen = RIGHT(@BenYue, 2)

  SET @NianFen = LEFT(@BenYue, 4)

  IF @YueFen IN ('01', '03', '05', '07', '08', '10', '12')

  BEGIN

   SET @ReturnValue = '31'

  END

  IF @YueFen IN ('04', '06', '09', '11')

  BEGIN

   SET @ReturnValue = '30'

  END

  IF @YueFen = '02'

  BEGIN

   IF ((@NianFen % 4 = 0 AND @NianFen % 100 <> 0) OR (@NianFen % 400 = 0))

   BEGIN

    SET @ReturnValue = '29'

   END

   ELSE

   BEGIN

    SET @ReturnValue = '28'

   END

  END

  RETURN @NianFen + '-' + @YueFen + '-' + @ReturnValue

 END