What is Normalization?

Normalization is the process that helps analysis or database designer to design table structure for an application. The focus of normalization is to attempt to reduce redundant table data to very minimum.

Normalization is carried out for the following reason:

1.     To structure the data between tables so that maintenance is simplified.

2.     To re allow data retrieval at optimal speed.

3.     To simplify data maintenance through update, insert & deletes.

4.     To reduce the need to restructure table as new application requirement arise.

5.     To improve the quality of design for an application by rationalization of table data.

Normalization is technique that:

1.     Decompose data into two dimensional tables

2.     Eliminate any relationship in which table data does fully depend upon the primary key of record.

3.     Eliminate any relationships that contain transitive dependencies.

FIRST NORMAL FROM:

When a table is decomposed into two dimensional table with all repeating group of data eliminated the table data is said to be in its first normal form.

The repetitive portion of data belonging to the record is treated as repeating groups.

A table is in 1^st normal form if:

·         There are no repeating groups.

·         All the key attribute are defined.

·         All attribute are dependent on a primary key.

To convert a table to its First Normal Form:

1.     The un-normalized data in the first table is the entire table.

2.     A key that will uniquely identify each record should be assigned to the table. This key has to be unique because it should be capable of identifying any specific row from the table for extracting information for use. This key is called the table’s primary key.

SECOND NORMAL FROM:

A table is said to be in its second normal form when each record in the table is in the first normal form & each column in the record is fully dependent on its primary key.

A table is in 2^nd normal form if:

·         It’s in 1^st normal form.

·         It include no partial dependencies (where as attribute is dependent on only a part of primary key)

To convert a table to its Second Normal Form:

1.     Find & remove fields that are related to the only part of the key

2.     Group the remove item in the another table

3.     Assign the new table with the key i.e. part of a composite key.

THIRD NORMAL FROM:

Table data is said to be in third normal form when all transitive dependencies are remove from this data.

A table is in 3^rd normal form if:

1.     It’s in 2^nd normal form.

2.     It contains no transitive dependencies (where a non-key attribute is dependent on another non –key attribute)