dsum issue

[Brian P.]

Hi there - I have a rather long qry involving inventory management.
I'm running a second qry, extracing three fields: Transaction Type
(buy/sell), Item Quantity (+/-), and Item Lot (LotID corresponds to a
date stored on a different table).

Is there some kind of DSum function that can sum up quantities of
identical LotID's? So far this has failed:

LotQty: DSum("[ItemQuantity]","[qryActivity]","[TransType]"=[buy])


I know I don't need the 3rd line here b/c in the initially qry I have
a quantity factor that multiplies all sells by -1, but how do I set up
the Group By statement for me to calculate individual lot totals?

Thanks,
Brian