From a Form subtract issue from bound QtyOnHand in a new record

I want to make a simple current record transaction and update one field in
the main database for a unique item. The transaction would be to add an
issue record to an issue table and change the inventory table QtyOnHand field
based on the issue. Update queries are generally for multiple records, I've
tried using the Default property without any luck

Paul,

Just my two cents here, but I would not store the Quantity on Hand in
a table. Storing "running totals" in databases is often a dangerous
thing to do. You are better off just storing all of the transactions,
and then getting the current QtyOnHand via a query/report whenever you
need to display it.