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The Normal Forms

The database community sets the few rules or guidelines for database normalization.

The Normal Forms


The Normal Forms

The database community sets the few rules or guidelines for database normalization. These rules are called as normal forms and starts from the first normal form till the fifth normal form. In this tutorial, we will only discussed about the most essential normal form such as 1NF, 2NF and 3NF.

First Normal Form (1NF)

The first normal form (1NF) sets the very crucial rule to create the database :

1. There are no repeating or duplicate fields.

2. Each cell contains only a single value.

3. Each record is unique and identified by primary key.

The normalization process involves getting our data to adjust in a progressive normal forms and you cannot achieve the higher level of normalization without satisfying the previous levels. The First Normal Form asking the values in each cell of a table must be atomic. The word atomic describes that there should be no sets of values in one particular cell.

Let's see the example below :

Prior to Normalization

Item Colors Price Tax
Pen red, blue 2.0 0.20
Scale red, yellow 2.0 0.20
Pen red, blue 2.0 0.20
Bag blue, black 150.00 7.80

This table is not in first normal form because :

  A. There are multiple fields in color lab.

  B. Records are repeating (Duplicate records) or no primary key.


First Normal Form (1NF)

Item Colors Price Tax
Pen red 2.0 0.20
Pen blue 2.0 0.20
Scale red 2.0 0.20
Scale yellow 2.0 0.20
Bag blue 150.00 7.80
Bag black 150.00 7.80

This table is now in first normal form.

In the next section, we will take a look on the Second form of Normalization.


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Posted on: January 28, 2010

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