Exam 2 - Quiz 6 (1)

Functional dependency

A constraint between two attributes in which the value of one attribute is determined by the value of another attribute.

Recursive foreign key

A foreign key in a relation that references the primary key values of the same relation.

Transitive dependency

A functional dependency between the primary key and one or more nonkey attributes that are dependent on the primary key via another nonkey attribute.

Partial functional dependency

A functional dependency in which one or more nonkey attributes are functionally dependant on part (but not all) of the primary key.

Relation

A named two-dimensional table of data.

Composite key

A primary key that consists of more than one attributes.

Enterprise key

A primary key whose value is unique across all relations.

Second normal form (2NF)

A relation in first normal form in which every nonkey attribute is fully functionally dependent on the primary.

Well structured relation

A relation that contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies.

First normal form (1NF)

A relation that has a primary key and in which there are no repeating groups.

Third normal form (3NF)

A relation that is in second normal form and has no transitive dependencies.

Entity integrity rule

A rule that states no primary key attribute (or component of a primary key attribute) may be null.

Referential integrity constraint

A rule that states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null.

Surrogate primary key

A serial number or other system-assigned primary key for a relation.

Normal form

A state of relation that requires that certain rules regarding relationships between attributes (or functional dependencies) are satisfied.

Null

A value that may be assigned to an attribute when no other value applies or when the applicable value is unknown.

Alias

An alternative name used for an attribute.

Foreign key

An attribute in a relation that serves as the primary key of another relation in the same database.

Primary key

An attribute or a combination of attributes that uniquely identifies each row in a relation.

Homonym

An attribute that may have more than one meaning.

Candidate key

An attribute, or combination of attributes, that uniquely indentifies a row in a relation.

Anomaly

An error or inconsistency that may result when a user attempts to update a table that contains redundant data. The three types of anomalies are insertion, deletion, and modification anomalies.

Determinant

The attribute on the left side of the arrow in a functional dependency.

Normalization

The process of decomposing relation with anomalies to produce smaller, well-structured relations.

Synonyms

Two (or more) attributes that have different names but the same meaning.