I have a problem that I originally thought was simple, but somehow became complicated....

I have two tables, both of which are out of my control, that stores invoices in one and the product cost that is effective from a certain date in another.

The structures are similar to:

Invoices - inv no, inv date, part no, quantity, etc...
Price list - part no, price, effective date

What I need to do, preferably in a query or set of queries, is to find the invoice value of all invoices between a certain period. This means that I must determine the correct value of each product when it was sold.

Any ideas, even the solution, would be gratefully received.


Jason