Chapter 6 - Normalization of Database Tables

atomic attribute

An attribute that cannot be further subdivided to produce meaningful components. For example, a person's last name attribute cannot be meaningfully subdivided.

denormalization

A process by which a table is changed from a higher-level normal form to a lower-level normal form, usually to increase processing speed. Denormalization potentially yields data anomalies.

dependency diagram

A representation of all data dependencies within a table.

determinant

Any attribute in a specific row whose value directly determines other values in that row.

first normal form (1NF)

The first stage in the normalization process. It describes a relation depicted in tabular format, with no repeating groups and a primary key identified. All nonkey attributes in the relation are dependent on the primary key.

key attributes

The attributes that form a primary key.

normalization

A process that assigns attributes to entities so that data redundancies are reduced or eliminated.

partial dependency

In normalization, a condition in which an attribute is dependent on only a portion of the primary key.

repeating group

In a relation, a characteristic describing a group of multiple entries of the same type for a single key attribute occurrence. For example, a car can have multiple colors for its top, interior, bottom, trim, and so on.

second normal form (2NF)

The second stage in the normalization process, in which a relation is in 1NF and there are no partial dependencies.

third normal form (3NF)

A table is in 3NF when it is in 2NF and no nonkey attribute is functionally dependent on another nonkey attribute; that is, it cannot include transitive dependencies.

transitive dependency

A condition in which an attribute is dependent on another attribute that is not part of the primary key.