Sample data
User Action DateTime
Smith inserted 22/7/2010 8:33
Andy inserted 22/7/2010 9:40
Steve collected 22/7/2010 10:01
Smith Update 22/7/2010 10:05
Scott inserted 22/7/2010 10:10
Paul inserted 22/7/2010 10:30
Smith collected 22/7/2010 10:45
Smith collected 22/7/2010 10:50
Smith deleted 22/7/2010 11:15
Smith inserted 22/7/2010 12:15
Desired output
User Action Time TimeDifference
Smith Inserted 22/7/2010 8:33
Smith deleted 22/7/2010 11:15
I need to find the time difference between Inserted(first) and deleted(before next inserted)