3rd Normal Form -3NF

People write entire books on logical and physical designs.  It will be hard to go into detail here.

You probably need to find another source other than Wikipedia to learn how to do a logical design.

Why use it:
It reduces stored redundant information.


When to use it:
You should always design the logical data model to at least 3NF.

Some will argue that the physical model should also be in 3NF.  I'm not sure I've ever seen a physical model in true 3NF.

Keys and Codd are easy:
Codd was sort of the createor of the rules for normalization.

Key is the unique identifier for an entity in the logical model and a primary key in the physical model.

You say "I have not understood clearly what it is talking about esp with respect to Key and Codd".

Does that mean you don't understand the concept of a primary key?  You don't know who E.F. Codd is ?

-- DaveSlash

>>How non key must provide a fact about a key

In a nutshell:
Every attribute in an entity must be directly related to the key for the entity.

Remember the quote I posted in your other question that I said I wasn't going to tell you what it meant?  Well this is what it means...