Actions - Set a value in Table A when a specific form from Table B is saved

Here is an example that I use int he app I cam currently building.

A bit of explanation, I want my Inventory to be updated when the Product row changes. In this example I am tracking Allocated amounts - meaning Products in Inventory that are “reserved” for scheduled Work Order.

I select the Inventory record using a SELECT() expression (the TOP() statement is not really needed since I only ever expect a single row).