i have report like that
Num open_date resolve_date group action_date
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 11:00
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 12:00
1 01.21.2013 10:00 01.21.2013 23:00 GRP3 01.21.2013 13:00
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 16:00
2 01.21.2013 12:00 02.21.2013 16:00 GRP6 01.21.2013 14:00
2 01.21.2013 12:00 02.21.2013 16:00 GRP7 01.21.2013 15:00
2 01.21.2013 12:00 02.21.2013 16:00 GRP6 01.21.2013 19:00
3 01.21.2013 22:00 02.21.2013 22:00 GRP9 01.21.2013 23:30
3 01.21.2013 22:00 02.21.2013 22:00 GRP9 01.22.2013 01:00
i need to calculate time difference action time with previous row for each Num record.
Num open_date resolve_date group action_date Diff
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 11:00 60
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 12:00 60
1 01.21.2013 10:00 01.21.2013 23:00 GRP3 01.21.2013 13:00 60
1 01.21.2013 10:00 01.21.2013 23:00 GRP1 01.21.2013 16:00 180
2 01.21.2013 12:00 02.21.2013 16:00 GRP6 01.21.2013 14:00 120
2 01.21.2013 12:00 02.21.2013 16:00 GRP7 01.21.2013 15:00 60
2 01.21.2013 12:00 02.21.2013 16:00 GRP6 01.21.2013 19:00 240
3 01.21.2013 22:00 02.21.2013 22:00 GRP9 01.21.2013 23:30 90
3 01.21.2013 22:00 02.21.2013 22:00 GRP9 01.22.2013 01:00 90
How to calculate time difference by previous row action date?
Thanks
iceice (BOB member since 2011-10-20)