I\'m working on an order system for my online shop. I have 2 tables:
At the very least you need:
Products (one row per product)
ProductID
Size
Orders (one row per order)
OrderID
OrderDetails (one row per product per order)
ProductID
OrderID
Size
Note that each 'size' is its own ProductID. You'll probably want to have yet another ID that groups products that are the same 'base' product, but in different sizes.
So if Order #1 has three products, and Order #2 has four, then OrderDetails
will have seven rows:
OrderID ProductID Quantity
1 234 2
1 345 9
1 456 30
2 432 1
2 234 65
2 654 8
2 987 4
Depends on your goals for your cart. For instance, do you want to allow guest purchases? i.e. where a user does not need to login in order to make a purchase?
The attached image is a design I have been working on and it goes like this:
A visitor selects products from the site and adds these to a session cart (just a place to temporarily store the products, their quantities and their prices etc.)
Once the customer is ready to check out, we create the order, the order person and the person_address (where the product must be delivered to) and add the items to the order_item table. All this information is added by the customer in the checkout page.
The final step is then to offer the payment methods: paypal, credit card, etc.
What I like about this design is that users have no obligation to register with us. Order_person acts as a kind of interface between users and orders. If do register, we simply link order_person to the user table...
I have included a sample front end of the checkout page too.