Avatar of gudii9
gudii9
Flag for United States of America asked on

3rd Normal Form -3NF

Hi,

I am going through below link
http://en.wikipedia.org/wiki/Third_normal_form


when and why to use the 3NF. I have not understood clearly what it is talking about esp with respect to Key and Codd. Please advice
Oracle DatabaseDB2Databases

Avatar of undefined
Last Comment
slightwv (䄆 Netminder)

8/22/2022 - Mon
slightwv (䄆 Netminder)

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.
Member_2_2484401

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
SOLUTION
momi_sabag

THIS SOLUTION ONLY AVAILABLE TO MEMBERS.
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
See Pricing Options
Start Free Trial
GET A PERSONALIZED SOLUTION
Ask your own question & get feedback from real experts
Find out why thousands trust the EE community with their toughest problems.
gudii9

ASKER
[Every] non-key [attribute] must provide a fact about the key,

what is meaning of this line. can you please elaborate. How non key must provide a fact about a key. It sounds strange to me.
All of life is about relationships, and EE has made a viirtual community a real community. It lifts everyone's boat
William Peck
slightwv (䄆 Netminder)

>>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...
gudii9

ASKER
Entity means Table right. Key means Primary key column right? Attribute(non-key) means non primary column? please advice about this terminology
ASKER CERTIFIED SOLUTION
slightwv (䄆 Netminder)

THIS SOLUTION ONLY AVAILABLE TO MEMBERS.
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
See Pricing Options
Start Free Trial
⚡ FREE TRIAL OFFER
Try out a week of full access for free.
Find out why thousands trust the EE community with their toughest problems.