Brilliant David, that's it. Thanks to all, jim

Thanks for the input so far. 

John you are right, it's three sessions, not two. 

Noel, the problem w this solution is that multiple creatives can be accessed in one...

Some test data might look like this

INSERT INTO pagehits

(id, sessionId, adate, creative)

VALUES

("402881030b2a2b5b010b2a3014ed0002", "934A30C24E5C56AA2223BE821B437554", getdate(), "402881030b2a2a47010b2a2aa8ba0014");

INSERT INTO pagehits

(id, sessionId, adate, creative)

VALUES

("402881030b2a2b5b010b2a302e4f0003", "28A7F824D3F88BF8DDA34A02A2B32467", getdate(),...

Thanks for your input.

The ID fields are integers, and stats are up to date. 

I'm more accustomed to working in Oracle, where there are various mechanisms for handling problems like...