Normalization in DBMS

Normalization in DBMS means decomposition of table to remove redundancy from table during organize the data in database.

Normalization in DBMS is done by using functional dependency.

Four mostly used normal form are:
1. First Normal Form or 1NF
2. Second Normal Form or 2NF
3. Third Normal Form or 3NF
4. Boyce Codd Normal Form or BCNF

First Normal Form or 1NF:

A table of database in First Normal Form or 1NF if and only if:
1. Every shell of a table should be atomic value. This means single value in a single shell of table.
2. Every column of table should contain the value of same domain.
3. Every column of table should have unique name.

Second Normal Form or 2NF:

A table of database in Second Normal Form or 2NF if and only if:
1. Table must be in First Normal Form or 1NF.
2. It should not contain partial dependency.

Partial dependency: Partial dependency means non prime attributes should not depends on all prime attributes.

Prime attributes: Prime attributes means an attribute which must be a part of the candidate key.

Candidate key: Candidate key is the efficient or minimal version of super key. It doesn’t have redundancy.

Third Normal Form or 3NF:

A table of database in Third Normal Form or 3NF if and only if:
1. Table must be in Second Normal Form or 2NF.
2. And Transitive dependency doesn’t exist.
OR
3. Every dependency from α->β:
a. Either α is super key.
b. or β is a prime attribute.

Transitive dependency: A functional dependency from α->β is called Transitive dependency if and only if α , β ∈ none prime attribute.

Boyce Codd Normal Form or BCNF:

A table of database in Boyce Codd Normal Form or BCNF if and only if:
1. Table must be in Third Normal Form or 3NF.
2. In α->β dependency α is must be super key.

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Another Topics of DBMS:
Entity Relationship Diagram or ER Diagram
Basics of Database Management System