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: WaxdollCheung
Date: 2004-04-04
*/

CREATEFUNCTIONdbo.Fun_YiYueDeZuiHouYiTian
(
@BenYueCHAR(6)
)
RETURNSCHAR(10)
AS
BEGIN
DECLARE@ReturnValueCHAR(2)
DECLARE@YueFenCHAR(2)
DECLARE@NianFenCHAR(4)

SET@YueFen=RIGHT(@BenYue,2)
SET@NianFen=LEFT(@BenYue,4)

IF @YueFenIN('01','03','05','07','08','10','12')
BEGIN
SET@ReturnValue='31'
END

IF @YueFenIN('04','06','09','11')
BEGIN
SET@ReturnValue='30'
END

IF @YueFen='02'
BEGIN
IF((@NianFen%4=0AND@NianFen%100<>0)OR(@NianFen%400=0))
BEGIN
SET@ReturnValue='29'
END
ELSE
BEGIN
SET@ReturnValue='28'
END
END

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