jdearden -
Your question is unclear. It sounds like you are trying to replace an existing shopping cart system with a new one of your own design. Is that correct?
Unless the existing shopping cart code is part of a widely distributed codebase (such as a PHP e-commerce package like MIVA Merchant), I seriously doubt Google is going to be much help 🙂 You need to look at the details of the specific implementation that you're working with. There is no universal model.
However, the usual approach to shopping carts is this:
You have a table named "products" (or something similar) which contains the name, price, ID number, and so forth of each product.
You also have a table named "users"; each user has a unique identifier.
And you have a table named "cart_items", which contains an ID column, a user_id column, a product_id column, and a quantity column.
Say George (user_id=88) adds five bags of monkey chow (product_id=7283) to his shopping cart. PHP will add the following record to the cart_items table:
user_id=88
product_id=7283
quantity=5
To display the contents of George's shopping cart, just "SELECT * FROM cart_items WHERE user_id=88;" (You'll probably want to join this query on the products table so you can get the name and price of each item, as well.)
Lastly, you have an orders table, and an order_items table. When George checks out, a new order record is created, containing his user ID, the shipping address, the shipping cost, and so forth. Each of George's cart_items is moved to the order_items table, which is keyed to the orders table.
It's also a good idea to copy the name, price, and other details of each item in the shopping cart to fields in the order_item record, in case these details change in the future. That way, you can look up old orders and be confident that you're seeing the information that was current at the time the order was placed.
Hope this makes sense...
