CREATE FUNCTION dbo.DATEDIFF360
(
	@source DATETIME,
	@target DATETIME,
	@style BIT = 0
)
RETURNS INT
AS
BEGIN
	RETURN	CASE @style
			-- European style
			WHEN 1 THEN	CASE
						WHEN DATEPART(DAY, @target) = 31 THEN 30
						ELSE DATEPART(DAY, @target)
					END
					- CASE
						WHEN DATEPART(DAY, @source) = 31 THEN 30
						ELSE DATEPART(DAY, @source)
					END
			-- US style
			ELSE	CASE
					WHEN DATEPART(DAY, @target) = 31 AND DATEPART(DAYOFYEAR, @source) = 60 AND DATEPART(MONTH, @source) = 2 THEN 30
					WHEN DATEPART(DAY, @target) = 31 AND DATEPART(DAY, @source) < 30 THEN 31
					WHEN DATEPART(DAY, @target) = 31 THEN 30
					ELSE DATEPART(DAY, @target)
				END
				- CASE
					WHEN @source = DATEADD(MONTH, DATEDIFF(MONTH, -1, @source), -1) THEN 30
					ELSE DATEPART(DAY, @source)
				END
		END + 30 * DATEDIFF(MONTH, @source, @target)
END