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Third Normal Form (1NF)

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The Third Normal Form has one more additional requirement

Third Normal Form (1NF)

     

Third Normal Form (1NF)

The Third Normal Form has one more additional requirement :

        A. It should meet all the requirements of the second normal form.

      B. It should remove columns that are not dependent upon the primary key.

In the Third Normal Form all columns depend upon the primary key. When one column depends upon the other column,  table break the rule and turns into the dependency on the primary key.      

Item Colors
Pen red
Pen blue
Scale red
Scale yellow
Bag blue
Bag black

 

Item Price Tax
Pen 2.0 0.20
Scale 2.0 0.20
Bag 150.00 7.80

 

Tables are not in Second Normal Form because tax depends on price, not item.

Item Colors
Pen red
Pen blue
Scale red
Scale yellow
Bag blue
Bag black

 

Item Price
Pen 2.0
Scale 2.0
Bag 150.00

 

Price Tax
2.0 0.20
150.00 7.80

Tables are now in Third Normal Form.

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Posted on: January 28, 2010

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Comments:2
Jaffar Hussain
February 14, 2013
Good & Simple explanation

Thanks , got to understand basics
anu
November 25, 2012
database

can i learn upto BCNF
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