The process of organizing data to minimize redundancy in the design of relational database management (RDBMS). It is also called as the normalization. Normalization generally involves dividing large tables into smaller, well formed tables and defining relationships between them. The objective of the normalization is to isolate the data so that additions, deletions, and modifications of a field can be made in just one table and then they can be propagated through the rest of the database via already defined relationships.
Database community has developed a series of guidelines called as normal forms for ensuring that databases are normalized. Following are the different normal forms:
First Normal Form (1NF):
It sets the basic rule for an organized database and it says eliminate the duplicate columns from the same table, create separate tables for each group of related data and identify each row with a unique column or set of columns.
Second Normal Form (2NF):
This form also addresses the concept of removing duplicate data, this rule says to meet all the requirements of the first normal form, remove subsets of data that apply to multiple rows of a table and place them in separate tables and create relationships between these new tables and their predecessors through the use of foreign keys.
Third Normal Form (3NF):
This normal form goes one step further, this rule implies to meet all the requirements of the second normal form and remove columns that are not dependent upon the primary key.
Fourth Normal Form (4NF):
Fourth normal form (4NF) has one more requirement in addition to the requirements of the third normal form and a relation is in 4NF if it has no multi valued dependencies.