Hi
I have two columns with date + time like this

Startdate Enddate
11/08/2004 19:00 11/08/2004 22:17
11/08/2004 19:30 11/08/2004 21:24
11/08/2004 22:30 11/08/2004 23:50
11/09/2004 00:00 11/09/2004 00:31
11/09/2004 00:30 11/09/2004 04:31
11/09/2004 02:00 11/09/2004 03:20
11/09/2004 15:00 11/09/2004 15:12

If i just sum up the difference in minutes between each row then I
will
get the total time in minutes but I'm looking for the effective time.

Some of the records are overlapping like record 1 and 2.
The effective time in record 1-2 is just 3h 17 minutes since record 2
fits inside the frame of the first record.

Is there an easy way to calculate this ?
Hope anyone can help
Stefan