# Types of Normalization

1NF: First Normal Form

Explains first normal form (1NF) in database design. An example of how to bring the database table structure to 1st normal form is shown.

source: 1keydata.com
2NF: Second Normal Form

In a table, if attribute B is functionally dependent on A, but is not functionally dependent on a proper subset of A, then B is considered fully functional dependent on A. Hence, in a 2NF table, all non-key attributes cannot be dependent on a subset of the primary key.

source: 1keydata.com
3NF: Third Normal Form

How are these addressed? By the third normal form. 3NF – Third Normal Form Definition. A table is in third normal form if: A table is in 2nd normal form. It contains only columns that are non-transitively dependent on the primary key; Wow! That’s a mouthful. What does non-transitively dependent mean? Let’s break it down.

BCNF: Boyce–Codd Normal Form

Nowadays the go-to normal forms are either the Boyce-Codd normal form (BCNF), which we will cover here today, or the third normal form (3NF), which will be covered later. (Yes, there are also the first, second, fourth, fifth normal form.

source: vertabelo.com
EKNF: Elementary key Normal Form

Elementary key normal form (EKNF) is a subtle enhancement on third normal form, thus EKNF tables are in 3NF by definition. This happens when there is more than one unique compound key and they overlap.

ETNF: Essential Tuple Normal Form

and join dependencies. ETNF lies strictly between fourth normal form and fth normal form (5NF, also known as projection-join normal form). We show that ETNF, al-though strictly weaker than 5NF, is exactly as e ective as 5NF in eliminating redundancy of tuples. Our de nition of ETNF is semantic, in that it is de ned in terms of tuple redundancy.

Fourth Normal Form

Fourth normal form (4NF) is a normal form used in database normalization. Introduced by Ronald Fagin in 1977, 4NF is the next level of normalization after Boyce–Codd normal form (BCNF).

UNF: Unnormalized Form

Unnormalized form (UNF), sometimes also known as an unnormalized relation or non first normal form (NF 2). It is generally characterized as being a simple database data model (organization of data in a database) lacking the efficiency of database normalization.