I have two tables; my primary table is a listing of our inventory units that we are running promotions for; when an inventory item sells, we add it's stock number to table 2. I'm looking for a way to set the status of each record in table 1 so that it shows as "for sale" if its stock number doesn't exist in table 2, and gets updated to "sold" when its stock number is added to table 2 as sold.
Any ideas on how to best achieve this?