What are different normalization forms?

1NF: Eliminate Repeating Groups 
Make a separate table for each set of related attributes, and give each table a primary key.
Each field contains at most one value from its attribute domain.

2NF: Eliminate Redundant Data 
If an attribute depends on only part of a multi‐valued key, remove it to a separate table.

3NF: Eliminate Columns Not Dependent On Key 
If attributes do not contribute to a description of the key, remove them to a separate table.
All attributes must be directly dependent on the primary key.

BCNF: Boyce‐Codd Normal Form 
If there are non‐trivial dependencies between candidate key attributes, separate them out
into distinct tables.


4NF: Isolate Independent Multiple Relationships 
No table may contain two or more 1:n or n:m relationships that are not directly related.

5NF: Isolate Semantically Related Multiple Relationships
There may be practical constrains on information that justify separating logically related
many‐to‐many relationships.

ONF: Optimal Normal Form 
A model limited to only simple (elemental) facts, as expressed in Object Role Model
notation.

DKNF: Domain‐Key Normal Form
A model free from all modification anomalies is said to be in DKNF.

Remember, these normalization guidelines are cumulative. For a database to be in 3NF, it
must first fulfill all the criteria of a 2NF and 1NF database.