How to get the number of days of the month in SQL Server sharing _mssql

As follows:

Copy Code code as follows:

CREATE FUNCTION [dbo]. [Udf_daysinmonth]
(
@Date DATETIME
)
RETURNS INT
As
BEGIN
DECLARE @dim as TABLE (M int,dy INT)
INSERT into @dim VALUES
(1,31), (3,31), (5,31), (7,31), (8,31), (10,31), (12,31),
(4,30), (6,30), (9,30), (11,30),
(2,
Case when (@Date)% 4 = 0 and year (@Date)% <> 0) OR (year (@Date)% 400 = 0)
THEN 29
ELSE End
)
DECLARE @RValue INT
SELECT @RValue = [Dy] from @dim WHERE [M] = MONTH (@Date)
Return @RValue
End
Go

Gets the number of days of the month that was previously written on the blog, but it only takes the number of days in February. Links are as follows: http://www.cnblogs.com/insus/articles/2025019.html
Now the first see the project in this function, always feel it is not good enough to write a feeling, whether it can rewrite it better, the inspiration Point is also from the February days of the case function to recall.
So I tried to change it as follows:

Copy Code code as follows:

CREATE FUNCTION [dbo]. [Udf_daysinmonth]
(
@Date DATETIME
)
RETURNS INT
As
BEGIN
Return case when MONTH (@Date) in (1,3,5,7,8,10,12) THEN 31
When MONTH (@Date) in (4,6,9,11) THEN 30
ELSE case if (@Date)% 4 = 0 and year (@Date)% <> 0) OR (year (@Date)% 400 = 0)
THEN 29
ELSE 28
End
End
End

If you already have a custom function that insus.net for February days, you can also refer to the following version:

Copy Code code as follows:

CREATE FUNCTION [dbo].[ Udf_daysinmonth]
(
@Date DATETIME
)
RETURNS INT
as
BEGIN
return case when MONTH ( @Date) in (1,3,5,7,8,10,12) THEN
when MONTH (@Date) in (4,6,9,11) THEN
ELSE [dbo].[ Daysoffebruary] (Year (@Date))
End
End