To speed up data retrieval

To structure data to avoid redundancy

To protect against bad data

To simplify complex topics

Storing different data types in one column

Using row order to convey information

Using repeating groups in a table

Having a primary key for each table

Removing transitive dependencies

Eliminating redundant data

Dependency on the entire primary key

Ensuring all attributes depend only on the primary key

Duplicate data existing in multiple places in a database

Inability to add new data without existing related data

Loss of all data related to an entity when one data item is removed

Incorrect data following an update operation

Third Normal Form

Second Normal Form

Boyce-Codd Normal Form

First Normal Form

Functional dependency

Multivalued dependency

Transitive dependency

Partial dependency

An attribute depends only on part of a composite key

An attribute depends on the whole primary key

An attribute depends on another attribute which itself depends on the primary key

Multiple attributes depend on a composite key

Fifth Normal Form

Fourth Normal Form

Third Normal Form

Second Normal Form

It has no multivalued dependencies

It cannot be decomposed into smaller tables without loss of data

It is free from update anomalies

It can be reconstructed by joining smaller tables

All forms of data redundancy

Multivalued dependencies independent of the primary key

Transitive dependencies

Partial dependencies