DECLARE @startDate	DATETIME,
		@endDate	DATETIME;

SET @startDate	=	'2009.04.15';
SET @endDate	=	'2009.04.30';

DECLARE @wholepart FLOAT;
DECLARE @fraction FLOAT;


IF(MONTH(@startdate)=MONTH(@enddate))
BEGIN
	IF (MONTH(@endDate)IN(1,3,5,7,8,10,12))
	BEGIN 
		SELECT @wholepart =DATEDIFF(MONTH,@startDate,@endDate) *1.0,
		@fraction =DATEDIFF(DAY,@startDate,DATEADD(DAY,1,@endDate)) *1.0/31.0
		SELECT ROUND(@wholepart+@fraction,0)
	END
	IF (MONTH(@endDate)IN(4,6,9,11)) AND (DAY(@startdate)>15)
	BEGIN 
		SELECT @wholepart =DATEDIFF(MONTH,@startDate,@endDate) *1.0,
		@fraction =DATEDIFF(DAY,@startDate,DATEADD(DAY,1,@endDate)) *1.0/30.0
		SELECT ROUND(@wholepart+@fraction,0)
	END
	IF(MONTH(@startdate)=2) AND (DAY(@startdate)>14)
	BEGIN		
		IF(YEAR(@startdate)%4=0)
		BEGIN
			SELECT @wholepart =DATEDIFF(MONTH,@startDate,@endDate) *1.0,
			@fraction = DATEDIFF(DAY,DATEADD(MONTH,@wholepart,@startDate),DATEADD(DAY,1,@endDate)) *1.0/29.0
		END
		ELSE
		BEGIN
			SELECT @wholepart =DATEDIFF(MONTH,@startDate,@endDate) *1.0,
			@fraction = DATEDIFF(DAY,DATEADD(MONTH,@wholepart,@startDate),DATEADD(DAY,1,@endDate)) *1.0/28.0
			SELECT ROUND(@wholepart+@fraction,0)
		END
	END
	ELSE
	BEGIN
			SELECT @wholepart =DATEDIFF(MONTH,@startDate,@endDate) *1.0,
			@fraction =DATEDIFF(DAY,DATEADD(MONTH,@wholepart,@startDate),@endDate) *1.0/
			CASE 
				WHEN MONTH(@endDate) IN (1,3,5,7,8,10,12)			THEN 31.0 
				WHEN MONTH(@endDate) IN (4,6,9,11)					THEN 30.0
				WHEN MONTH(@endDate)=2 AND (YEAR(@endDate)%4 = 0)	THEN 29.0
				ELSE 28.0 
			END
	END
END
--ELSE Block Missing
SELECT @wholepart+@fraction
SELECT round(@wholepart+@fraction,0)