Database optimization orders

Question

In a database where users can place orders, is it better to have a new table with addresses or each order has the address data in its header.

Answer 1

In general you will most likely want to separate:

• Users
• Addresses
• Order information

This is because users can change address over time, but old addresses need to be kept because they have orders against them. Plus a single user can have multiple orders from the same address, so we separate out this information to reduce duplication.

http://en.wikipedia.org/wiki/Database_normalization