获取某个月的总天数

IF OBJECT_ID('dbo.Fun_GetMonthDays') IS NOT NULL DROP FUNCTION dbo.Fun_GetMonthDays
GO
-- =============================================
-- Author:		yenange
-- Create date: 2018-07-03
-- Description:	获取某个月的总天数
-- =============================================
CREATE FUNCTION dbo.Fun_GetMonthDays 
(
	@yyyyMM VARCHAR(20)
)
RETURNS INT
AS
BEGIN
	DECLARE @r INT
	SET @yyyyMM=CAST(REPLACE(REPLACE(@yyyyMM,'-',''),'/','') AS CHAR(6))
	DECLARE @dayFirst DATETIME
	SET @dayFirst=LEFT(@yyyyMM,4)+'-'+RIGHT(@yyyyMM,2)+'-01'
	SELECT @r= DATEDIFF(DAY,@dayFirst,DATEADD(MONTH,1,@dayFirst))
	RETURN @r;
END
GO
SELECT dbo.Fun_GetMonthDays('2018-06-01'),dbo.Fun_GetMonthDays('2018-07-15')