Database Normalisation

What is Database Normalisation?
Normalization is the process of organizing data in a database.

Normalisation process achieves,
a. Elimination of redundant data (Hence storage space reduced).
b. Ensure data dependency makes sense (Hence ensures data stored logically).

Database Normalisation is achieved by applying some rule called "Normal Form"

There are various levels of normalisation that can be done on databases,

1. First Normal Form:
a. Eliminate repeating groups in individual tables.
b. Create a separate table for each set of related data.
c. Identify each set of related data with a primary key.

2. Second Normal Form:
a. Meet all the requirements of the First normal form.
b. Create separate tables for sets of values that apply to multiple records.
c. Relate these tables with a foreign key.

3. Third Normal Form:
a. Meet all the requirements of the Second normal form.
b. Eliminate fields that do not depend on the key

4. Fourth Normal Form:
Fourth normal form, also called Boyce Codd Normal Form (BCNF), and fifth normal form do exist, but are rarely considered in practical design.