Hi,


can anyone help with this, please? I've got a simple database with two tables: customer and product table. Each single product can be sold only once to one customer but one customer can buy one or more products. I've got a products form and I'd like, when I fill in all the product related fields in this form, the last field to be a list of old customers to chose from to assign the customer to the product or if it's an old customer to click button to open customer form in an add mode and add a new customer and assign him to the product.

I'd like also one of the fields on the form to be calculated from other three fields on the same form (and from the same table) but even after a good research I still haven't managed to make it working. it should be something like field 4= field 3 -field 2 - field 1

Hope this all makes a sense . This is my first database and any suggestions will be highly appreciated.
Many thanks.