Re: How to represent a Specification in the Relational model

> Interesting idea. But "no subproduct specified" isn't exactly the same
> thing as "Generic". For instance, retrieve all of the orders without
> any subproduct specified.

I reread your original post. Didn't catch that "Specifying just a product and no subproduct means any Toaster." So, a customer can either order:
1) a specific product
2) or specify a product category

This level of flexibility might require:

T_Thing
1 Toaster
2 GE Toaster 3000
3 BD Toaster MX-34
4 Blender
5 GE Blender 5000

T_SubCat

Toaster     GE Toaster 3000
Toaster     BD Toaster MX-34
Blender     GE Blender 5000

T_Order
Order1
Order2
Order3

T_OrderThing
Order1 Toaster
Order1 GE Blender 5000
Order2 BD Toaster MX-34
Order3 Blender Received on Wed Jan 10 2007 - 17:29:38 CET