Dear Larry,
I thought you might be interested in my thoughts on your design for the E-Commerce product in your PHP6 and MySql book
Normalising the E-Commerce data
An invoice for a transaction would include the following fields:
TABLE0 order_id, date, cust_id, cust_name,{print_id, print_name, price, size,desc, image, artist_id, artist_name, qty}*
The fields in brackets are the repeated order items. This data is not normalised.
First Normal Form states: 1. no repeating data 2. each column (field) must be atomic
So, separating out the repeats and expanding the names, (PK = Primary