sql>select date1, date2,
2 ((date2 - date1) * 24) -
3 decode(trunc(date2) - trunc(date1),
4 0, 0,
5 (trunc(date2) - trunc(date1)) * 15.5) elapsed_hours
6 from t2
7 order by date1;
DATE1 DATE2 ELAPSED_HOURS
------------------- ------------------- -------------
07/16/2002 10:22:00 07/16/2002 16:37:00 6.25
07/16/2002 14:34:00 07/17/2002 10:17:00 4.2166667
07/17/2002 09:37:00 07/17/2002 10:37:00 1
07/18/2002 16:19:00 07/20/2002 16:19:00 17
07/18/2002 16:30:00 07/18/2002 17:00:00 .5
07/18/2002 17:00:00 07/19/2002 09:00:00 .5
07/19/2002 17:00:00 07/20/2002 17:00:00 8.5