What is Normalization in DBMS ?

webmaster — Fri, 27 May 2022 06:39:14 +0000

Normalization is a process of breaking down the relations with a less attributes.
Process of arranging the data in the database is called Normalization.
To reduce the repetition from a relation or from a set of relations, normalization is used.
It is used for removing undesirable characteristics like Insertion, Update and Deletion Anamolies.
Normalization divides larger table into smaller by linking them using relationships.
To reduce the repetition from a database table, normal forms are used.
For removing anamolies from relations, we use normalization.
If the anamolies are not eliminated, it may lead to data repetition, and it can also cause data integrity and other problems when the data base grows.
For creating a good database certain rules and regulations are set in normalization.

What is Normalization ?

Editor — Mon, 19 Jul 2021 10:33:39 +0000

Normalization is the process of reorganizing data in a database. They have two basic requirements they are:
- No redundancy of data.
- Logical as data dependencies.
To normalize a database, we divide the database into tables and establish relationships between the tables.
Database normalization can essentially be defined as the practice of optimizing table structures.
Optimization is accomplished as a result of a thorough investigation of the various pieces of data that will be stored within the database, in particular concentrating upon how this data is interrelated.

The First Normal Form should be following some rules in table,
- It should only have single(atomic) valued attributes/columns.
- Values stored in a column should be of the same domain
- All the columns in a table should have unique names.
- And the order in which data is stored, does not matter.

For a table to be in the Second Normal Form,
- It should be in the First Normal form.
- And, it should not have Partial Dependency.

A table is said to be in the Third Normal Form when,
- It is in the Second Normal form.
- And, it doesn’t have Transitive Dependency.

Boyce and Codd Normal Form is a higher version of the Third Normal form. This form deals with certain type of anomaly that is not handled by 3NF. A 3NF table which does not have multiple overlapping candidate keys is said to be in BCNF.
For a table to be in BCNF, following conditions must be satisfied:
- R must be in 3rd Normal Form and, for each functional dependency ( X → Y ), X should be a super Key.

A table is said to be in the Fourth Normal Form when,
- It is in the Boyce-Codd Normal Form.
- And, it doesn’t have Multi-Valued Dependency.

Fifth Normal Form (5NF), also known as project-join normal form (PJ/NF) is a level of database normalization designed to reduce redundancy in relational databases recording multi-valued facts by isolating semantically related multiple relationships.
A relation R is in Fifth Normal Form (5NF) and only if the following conditions are satisfied simultaneously,
- R is already in 4NF.
- It cannot be further non-loss decomposed.