Key Terms Chapter 7

Anomalous behavior	A situation in which an update to one value affects another value
Boyce-Codd normal form (BCNF) schema	A schema in which every nontrivial functional dependency has a superkey on the left side.
Decomposition	The process of dividing a schema into two smaller schemas, often for the purpose of removing a normal form violation
Deletion anomaly	A situation, usually caused by redundancy in the schema, in which the deletion of one row of a table results in the deletion of an unintended information
Determinant	The attributes on the left side of a functional dependency that determine the attributes on the right side
Functional dependency	The situation in which the values of one set of attributes determine the values of another set
Insertion anomaly	A situation, usually caused by redundancy in the schema, in which the insertion of a row in a table creates an inconsistency with other rows
Modification anomaly	A situation, usually caused by redundancy in the schema, in which the modification of a row of a table creates an inconsistency with another row
Non-key attribute	An attribute in a relation schema that is not part of any key of the relation schema
Normal form	A collection of rules that describes an acceptable form of a relation schema
Normalization	A process of modifying a relation schema so that it conforms to certain rules called normal forms. Normalization is conducted by evaluating a relation schema to find violations of the particular rules, and then decomposing the schema into smaller, related schemas that do not violate the rules
Key	A superkey which is minimal in the sense that removing any attribute from it produces a set of attributes that is not a superkey
Key attribute	An attribute in a relation schema that is part of some key of the schema
Redundancy	The duplication of information in multiple tables within a database
Schema improvement	The modification of a schema to improve its design, especially so that each table will have a simple meaning, and so that the database will have less duplication of information and fewer null values
Superkey	A set of attributes of a relation schema that together determine the rest of the attributes of the schema. Alternatively, the left side of a functional dependency that includes all of the attributes of a schema. Every key is also a superkey
Superkey dependency	A functional dependency that includes every attribute of the schema.
Third normal form (3NF) schema	A schema in which every functional dependency has either a superkey as determinant or key attributes on its right side
Update anomaly	A situation, usually caused by redundancy in the schema, in which an update to one value affects another value. An update anomaly may be a deletion anomaly, an insertion anomaly, or a modification anomaly

Anomalous behavior

A situation in which an update to one value affects another value

Boyce-Codd normal form (BCNF) schema

A schema in which every nontrivial functional dependency has a superkey on the left side.

Decomposition

The process of dividing a schema into two smaller schemas, often for the purpose of removing a normal form violation

Deletion anomaly

A situation, usually caused by redundancy in the schema, in which the deletion of one row of a table results in the deletion of an unintended information

Determinant

The attributes on the left side of a functional dependency that determine the attributes on the right side

Functional dependency

The situation in which the values of one set of attributes determine the values of another set

Insertion anomaly

A situation, usually caused by redundancy in the schema, in which the insertion of a row in a table creates an inconsistency with other rows

Modification anomaly

A situation, usually caused by redundancy in the schema, in which the modification of a row of a table creates an inconsistency with another row

Non-key attribute

An attribute in a relation schema that is not part of any key of the relation schema

Normal form

A collection of rules that describes an acceptable form of a relation schema

Normalization

A process of modifying a relation schema so that it conforms to certain rules called normal forms. Normalization is conducted by evaluating a relation schema to find violations of the particular rules, and then decomposing the schema into smaller, related schemas that do not violate the rules

Key

A superkey which is minimal in the sense that removing any attribute from it produces a set of attributes that is not a superkey

Key attribute

An attribute in a relation schema that is part of some key of the schema

Redundancy

The duplication of information in multiple tables within a database

Schema improvement

The modification of a schema to improve its design, especially so that each table will have a simple meaning, and so that the database will have less duplication of information and fewer null values

Superkey

A set of attributes of a relation schema that together determine the rest of the attributes of the schema. Alternatively, the left side of a functional dependency that includes all of the attributes of a schema. Every key is also a superkey

Superkey dependency

A functional dependency that includes every attribute of the schema.

Third normal form (3NF) schema

A schema in which every functional dependency has either a superkey as determinant or key attributes on its right side

Update anomaly

A situation, usually caused by redundancy in the schema, in which an update to one value affects another value. An update anomaly may be a deletion anomaly, an insertion anomaly, or a modification anomaly