About Normalization

Normalization

     Normalization is a process of discarding repeating groups, minimizing redundancy, eliminating composite key.

     Through the normalization process, the collection of data in a single table is replaced by the same data being distributed over multiple tables with a specific relationship being setup between the tables.

     By this process RDBMS schema designers try their best to reduce table data to the very minimum.

O Types of Normalization

     First Normal Form

            when a table is decomposed into two dimensional tables    

        with all repeating groups of data eliminated the table data   

        is said to be in its first normal form.

• A table is in 1^st normal form if

            1> There are no repeating groups.

            2> All the key attributes are defined.

            3> All attributes are dependent on a primary key.

Exmple:-

Emp table

Field	Key
Project no	--
Projectname	--
Empno	--
empname	--
Rate category	--
Hourly rate	--

First normalization

Field	Key
Project no	Primary key
Projectname	--
Empno	Primary key
empname	--
Rate	--

Second Normalization

     Table: Empproj  

Field	Key
Projectno	Primary key
Empno	Primary key

     Table: Emp

Field	Key
Empno	Primary key
empname	--
Rate category	--
Hourly rate	--

     Table: proj

Field	Key
Project no	Primary key
Projectname	--

Third Normalization

     Table: Empproj

Field	Key
Projectno	Primary key
Empno	Primary key

     Table: Emp

Field	Key
Empno	Primary key
empname	--
Rate	--

     Table: Rate

Field	Key
Rate category	Primary key
Hourly rate	--

     Table: proj

Field	Key
Project no	Primary key
Projectname	--