Interval manipulation

does anyone know of a way to get an interger value representing the number of minutes interval between to values stored as datetime year to minute as opposed to "days hh:mm" as in the following: select d1,d2,d1 - d2 order by 3 1992-10-21 16:29 1991-01-18 10:10 642 06:19 1992-09-29 13:15 1991-01-07 15:00 630 22:15 1992-10-02 00:46 1991-02-05 06:47 604 17:59 1992-10-01 01:21 1991-02-22 11:21 586 14:00 1992-09-29 12:53 1991-02-28 18:05 578 18:48