Data Normalization

Data Normalization

In this section you will learn the concepts of data normalization. The most important thing in database designing is to make sure that the data get properly distributed among the tables. Simply we can say that the designing of  the table in proper manner is called Normalization.

Normalization is a process that is used in relational database design to organize the data for minimizing the duplication. In normalization, we divide the database in two or more tables and create a relationship between them. After isolating the data we perform some addition, deletion or modification on the fields of a table then we propagate and remove the duplicate data from the related tables.

The main goals of normalization process are: 
- To eliminate the redundancy of data
- To make sure that the data dependencies (relationship) make sense.
By these two goals we reduce the space occupied by the duplicate data in the database tables and ensure that the data is logically stored there.

Some of the positive points of the data normalization in database is as under :

Data integrity
To make optimized queries on the normalized tables and produce fast, efficient results.
To make faster index and also make a perfect sorting.
To increase the performance of the database.

First normal Form (1NF)
The First Normal Form requires the atomic values in each column. Atomic means the set of values are not available with in the column. In other words, in First Normal Form table must have at least one candidate key and make sure that the table don?t have any duplicate record. In First Normal Form repeating groups are not allowed, that is no attributes which occur a different number of times on different records.

Second normal Form (2NF)
The Second Normal Form can be achieved only when a table is in the 1NF. We can make the 2NF by eliminating the partial dependencies. As the First Normal Form deals with only the atomicity of data, but Second Normal Form deals with the relationships of tables like composite keys and non-key columns. In Second Normal Form subset of data is removed and is organized in separate tables. This process is applied to multiple rows of a table till the duplicity get reduced.

Third Normal Form (3NF)
The Third Normal Form can be achieved only when a table is in the Second Normal Form. We can make the 3NF by eliminating all transitive dependencies lying among the fields of a record. In Third Normal Form, all columns should depend on the primary key only i.e. remove the column, which is not dependent upon the primary key.
 
Boyce-Codd Normal Form (BCNF)
In the normalization Boyce - Codd Normal Form needs a table to meet the Third Normal Form. In Boyce - Codd Normal Form every non-trivial functional dependency must be a dependent on a superkey.

Fourth Normal Form (4NF)
The Fourth Normal Form can be achieved when a table meets the Boyce-Codd Normal Form. Fourth Normal Form confirms that the independent multivalued facts are efficiently and correctly represented in database design.

Fifth Normal Form (5NF)
The Fifth Normal Form is achieved only when a table meets the Fourth Normal Form. In this normalization it is ensured that all non-trivial join dependencies get eliminated.