Please excuse my lack of ability to properly ask this question. I'll do my best.
I have 2 tables, "TO1_Instruments" and "TO2_Upload". I've created a field in TO1 (TO1_supplier) that I would like to populate with data from TO2 (TO2_supplier). I would like this relationship to first examine the field "serial_number" for a match. If that field is blank, I would like the relationship to move on to the field "item_code" for a match. I would like this to be a one time lookup that doesn't continually update. I would be super bonus if it made me aware if there is more than one match with contradicting info in the field "supplier".
Thanks for any help.