Normalization of Database Tables

Normalization Stages

1NF, 2NF, and 3NF

Partial Dependency

A dependency based on only a part of a composite primary key.

4NF

A table where all attributes are dependent on the primary key but are independent of each other, and no row contains tow or more multivalued facts about an entity.

BCNF

A table where every determinant is a candidate key.

Prime Attribute

An attribute that is part of a key

Repeating Group

A collection of multiple entries of the same type can exist for any single key attribute occurrence.

Normalization

A process to help reduce the likelihood of data anomalies.

Crow's Foot notation ERD

A specific type of ERD

1NF

A table that has all key attributes defined, has no repeating groups, and all its attributes are dependent on the primary key.

2NF

A table that is in 1NF and includes no partial dependencies.

3NF

A table that is in 2NF and contains no transitive dependencies.

Determinant

Any attribute whose value determines other values within a row.

Atomic Attribute

Cannot be further subdivided

ERD

Created through an iterative process. Provides the big picture, or macro view, of an organizations's data requirements and operations. A technique used by database designers to construct a data model with a new database structure based on the business requirements of the end users.

Multivalued Dependency

One key determines multiple values of two other attributes and those attributes are independent of each other.

Dependency Diagram

Provides a bird's eye view of all the relationships among a table's attributes, and their use makes it less likely that you will overlook an important dependency.

Granularity

The level of detail represented by the values in a table's row.

Transitive dependency

When there are functional dependencies such that Y is functionally dependent on X, Z is functionally dependent on Y, and X is the primary key.

Data Redundancy

Yields anomalies