TSQL İki tarih arası fark.

DECLARE @ilktar datetime = '2010-01-01 08:15:00.0',
                 @sontar datetime = '2011-08-17 19:00:35.0'

SELECT
     DATEDIFF(YEAR,@ilktar,@sontar)        AS [Yıl]
    ,DATEDIFF(MONTH,@ilktar,@sontar)     AS [Ay]
    ,DATEDIFF(WEEK,@ilktar,@sontar)       AS [Hafta]
    ,DATEDIFF(DAY,@ilktar,@sontar)           AS [Gün]
    ,DATEDIFF(HOUR,@ilktar,@sontar)       AS [Saat]
    ,DATEDIFF(MINUTE,@ilktar,@sontar)    AS [Dakika]
    ,DATEDIFF(SECOND,@ilktar,@sontar)  AS [Saniye]








Kaynak : http://msdn.microsoft.com/en-us/library/ms189794.aspx