Simple User Interface - Interactive form

[gregtriplett]

I've got 3 tables. One for "products", one for "customers", and one that shows which products go with each customer. This 3rd table is called "product_to_customer" table. I'd like to create a form that provides a simple user interface where the user enters a customer name and a product name. If the customer name and product name are already in the their respective tables the form automatically enters the product and customer information into the "product_to_customer" table to show the desired new product/customer relationship. If either the product name is not already in the "products" table and/or if the customer name is not already in the "customers" table the form automatically enters this new product and/or new customer into the respective tables and then also makes an entry into the "product_to_customer" table to show their relationship. Can anyone get me started on this? Thanks in advance...