add a field from one table to a field in another table

[Guest]

I want to Assign parts on one form by job number and quantity and want it to
automaticaly subtract from inventory on another table

 

[Al Camp]

Tmiller,
Not much info to go on, but...
Usually in any Inventory system, a Disbursement should not involve
"deleteing" a corresponding Part from stock.
Rather, Parts are received as + transactions, Disbursements are handled
as - transactions, and the actual OnHand is the sum of all those
transactions.
Actually, the best way is to have a table that contains both Receiving
and Disbursing records, in one table. Think of your inventory system as
just a "checkbook" Money come in and money goes out... from the same table.
The sum, at any time, is the balance.