Database Normalization

First Normal Form (1NF)
- A relation is in first normal form if and only if the domain of each attribute contains only atomic (indivisible) values, and the value of each attribute contains only a single value from that domain.

1NF Criteria:
- Eliminate repeating groups[clarification needed] in individual tables
- Create a separate table for each set of related data
- Identify each set of related data with a primary key

Second Normal Form (2NF)
A relation is in the second normal form if it fulfills the following two requirements:

- It is in first normal form.
- It does not have any non-prime attribute that is functionally dependent on any proper subset of any candidate key of the relation. A non-prime attribute of a relation is an attribute that is not a part of any candidate key of the relation.

* "There should be no partial dependency"

Third Normal Form (3NF)
- The entity is in second normal form.
- No non-prime (non-key) attribute is transitively dependent on any key i.e. no non-prime attribute depends on other non-prime attributes. All the non-prime attributes must depend only on the candidate keys.

* it should not have Transitive Dependency.


Additional readings:

https://www.studytonight.com/dbms/database-normalization.php
https://www.studytonight.com/dbms/first-normal-form.php
https://www.studytonight.com/dbms/second-normal-form.php
https://www.studytonight.com/dbms/third-normal-form.php