Normalization

what is Normalization?

It's the process of efficiently organizing data in a database.

Goals of the Normalization:

1.Eliminate redundant data
2.Ensure data dependencies make sense

The database community has developed a series of guidelines for ensuring that databases are normalized. These are referred to as normal forms and are numbered from one (the lowest form of normalization, referred to as first normal form or 1NF) through five (fifth normal form or 5NF).

In practical applications, you'll often see 1NF, 2NF, and 3NF along with the occasional 4NF.
Fifth normal form is very rarely seen.

First normal form (1NF) sets the very basic rules for an organized database:

* Eliminate duplicative columns from the same table.
* Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).

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Second normal form (2NF) further addresses the concept of removing duplicative data:

* Meet all the requirements of the first normal form.
* Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
* Create relationships between these new tables and their predecessors through the use of foreign keys.

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Third normal form (3NF) goes one large step further:

* Meet all the requirements of the second normal form. * Remove columns that are not dependent upon the primary key.

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Finally, fourth normal form (4NF) has one additional requirement:

* Meet all the requirements of the third normal form.
* A relation is in 4NF if it has no multi-valued dependencies.