Intro to DBMS

Normalization

  • Normalization is the process of organizing the data in the database.
  • It is used to remove or minimize the redundancy from a relation
  • Keep in mind, while minimizing the redundancy, that functional dependency rules aren’t violated.

Normalization uses different types of normal forms to reduce redundancy from the database table.

Types of Normal Forms

There are four types of normal forms

 

Normal Form  Description
1NF A relation will be in 1NF if it contains an atomic value.
2NF A relation will be in 2NF if it follows the following

• It is in 1NF
• All non-key attributes are fully functional and dependent on the primary key.

3NF A relation will be in 3NF if it follows the following

• It is in 2NF
• It has no transition dependency exists.

BCNF A relation will be in BCNF if it follows the following

  •  It should be in 3NF
  • For every FD, LHS is a candidate key or super key.
4NF A relation will be in 4NF if it follows the following
• It is in Boyce Codd’s normal form
• It has no multi-valued dependency.
5NF A relation is in 5NF if it follows the following
• It is in 4NF
• It does not contain any join dependency, and joining should be lossless.