返回当月天数

1 CREATE function [dbo].[返回当月天数]
2 (
3 @yearmonth varchar(6) --参数格式：年月
4 )
5 returns int
6 as
7 begin
8 return (datediff(d,@yearmonth+'01',dateadd(mm,1,@yearmonth+'01')))
9 end