This should help you

DECLARE@table TABLE

(

IDINT,

StartDateDATETIME,

EndDateDATETIME

)

INSERT@table( ID, StartDate, EndDate )

SELECT1, '2013-02-17 10:33:10', '2013-02-17 20:14:40' UNION ALL

SELECT1, '2013-02-13 12:42:55', '2013-02-14 14:30:50' UNION ALL

SELECT1, '2013-02-12 15:04:32', '2013-02-15 12:22:25' UNION ALL

SELECT1, '2013-02-16 20:08:18', '2013-02-18 02:10:10'

SELECTT.ID, T.StartDate, T.EndDate,

CASE

WHEN DATEADD( DAY, DATEDIFF( DAY, T.StartDate, T.EndDate ), T.StartDate ) <= T.EndDate

THEN DATEDIFF( DAY, T.StartDate, T.EndDate )

ELSE DATEDIFF( DAY, T.StartDate, T.EndDate ) - 1

END + --====================Gives you the days

(

CASE

WHEN DATEADD( MINUTE, DATEDIFF( MINUTE, T.StartDate, T.EndDate ), T.StartDate ) <= T.EndDate

THEN DATEDIFF( MINUTE, T.StartDate, T.EndDate )

ELSE DATEDIFF( MINUTE, T.StartDate, T.EndDate ) - 1

END % ( 60 * 24 )

) / 1440.00 AS Result --===============Gives you the hours in decimals

FROM@table AS T

Edit: Added some comments and changed the query( "<" condition changed to "<=" )