Very difficult qns!!! How to derive entry and exit time from 1 messy db.

Hi all,
I am faced with a very troubled scenario. I am given a .mdb from access 2003. The data are so messy and i am tasked to derive the working hrs. After trying for quite some time, i still unable to get it. Therefore have to post it here, hoping that some pro here can help me derive the sql statements.


TACS table:
EventDate StaffName EventTime Message
21/11/12 John 23:01:00 OUT
21/11/12 Peter 23:10:00 IN
21/11/12 Peter 23:10:05 IN
22/11/12 John 07:19:00 IN
22/11/12 Peter 07:20:00 OUT
22/11/12 Joe 07:30:00 IN
22/11/12 Mike 08:00:00 IN
22/11/12 John 17:00:00 OUT
22/11/12 John 17:01:00 OUT
22/11/12 Joe 19:01:00 OUT
22/11/12 Mike 19:30:00 OUT
22/11/12 Mary 22:00:00 IN
23/11/12 John 07:01:00 IN
23/11/12 Mary 08:00:00 OUT
23/11/12 Peter 09:00:00 IN


What i want to derive.
FinalTable:
ID EntryDT ExitDT SName WrkHrs
1 Unknow 21/11/12 23:01:00 John Unknown
2 21/11/12 23:10:05 22/11/12 07:20:00 Peter 8hrs10mins
3 22/11/12 07:19:00 22/11/12 17:00:00 John 9hrs41mins
4 22/11/12 07:30:00 22/11/12 19:01:00 Joe 11hrs31min
5 22/11/12 08:00:00 22/11/12 19:30:00 Mike 11hrs30min
6 22/11/12 22:00:00 23/11/12 08:00:00 Mary 10hrs
7 23/11/12 07:01:00 Unknow John Unknown
8 23/11/12 09:00:00 Unknow Peter Unknown


My logic is that first check the message is it in or out. In signifies clockIn. If there are multiple clock in before out, i will use the latest clockIn as EntryDT, and vice versa, use the latest clockOut as ExitDT. However due to the mess, i dk how to write a statement to allow the prog to know which timing are for which event. Lastly if there are no respective clock in or out, it will be left unknown.

Any help will be greatly appreciated.

Thanks,
10e5x