Three customer addresses in one table or in separate tables?

Question

In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class:

Answer 1

I'd go with denormalized. It's easier.

If you normalize it, the address table would require you to remove duplicates and relink records from the customer table. If I had the same delivery and invoice address, it seems like it should link to the same record. If I change one, you're required to:

1. Create a new address record.
2. Relink the customer record.

If I change it back you need to check:

1. Does a similar address entry already exist.
2. Relink the customer record.

This programming overhead seems to obviate the advantage of less space that normalization seems to offer. A denormalized solution, like you pointed out, would provide faster queries and easier maintenance (programming-wise). This seems to be the deciding factor for me.

A normalized solution, like pointed out above, would allow you to add more addresses later. But you'd have to add a field for the foreign key anyways, unless you planned on organizing the tables without linkage from the customer to the address table.

Advantages of Normalized

• Less space.
• Duplicate logic kinda built in (though maybe they weren't actually duplicates?)
• Support addition of new address fields (kinda).

Advantages of Denormalized

• Faster queries.
• Less programming.