Dias del Mes en SQL

Funcion asincrona para calcular los dias del mes de una fecha dada, muy util en ciertos casos

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

– =============================================
– Author:
– Create date: <10/10/2009>
– Description:
– =============================================
ALTER FUNCTION [dbo].[ufn_DiasDelMes] ( @pDate DATETIME )
RETURNS INT
AS
BEGIN

RETURN CASE WHEN MONTH(@pDate) IN (1, 3, 5, 7, 8, 10, 12) THEN 31
WHEN MONTH(@pDate) IN (4, 6, 9, 11) THEN 30
ELSE CASE WHEN (YEAR(@pDate) % 4 = 0 AND
YEAR(@pDate) % 100 != 0) OR
(YEAR(@pDate) % 400 = 0)
THEN 29
ELSE 28
END
END

END

Ya declarada, su uso es sumamente simple:

Select ufn_DiasDelMes(Fecha) as Meses From Tabla