I have a table with a list of transactions (invoices and credits) and I need to get a list of all the rows where the invoices and credits don't match up.

eg

user     product    value
bill     ThingA     200
jim      ThingA    -200
sue      ThingB     100
liz      ThingC      50

I only want to see the third and fourth rows, as the values of the others match off.

I can do this if I select product, sum(value) ... group by product having sum(value) <> 0

which works well, but I want to return the user name as well.

As soon as I add the user to the select, I need to group by it as well, which messes it up as the amounts don't match up by user AND product.

Any ideas ? I am using MS SQL 2000...

Cheers