How do I subtract numbers in a column from one table to another?

[Guest]

What I am trying to do is have two separate tables. One is for current
inventory and one for inventory disbursement. I would like to have the
quantity column in the current inventory table updated automatically when
inventory is used (which info would come from the inventory disbursement
table quantity column).

 

[Guest]

What I am trying to do is have two separate tables. One is for current

inventory and one for inventory disbursement. I would like to have the
quantity column in the current inventory table updated automatically when
inventory is used (which info would come from the inventory disbursement
table quantity column).

If you look at the Inventory Management Template (relationships window) on
the Microsoft site:

http://office.microsoft.com/en-us/templates/TC010184581033.aspx?CategoryID=CT011366681033

you will see that all inventory transactions are kept in the same table.
You then use a form that can show you what has been ordered/received/sold,
along with the number of units on hand or on order. It is very much like
having a paper ledger that has all transactions put into it, except that you
let the database do all the work of adding and subtracting numbers.