Database Chapter 5.1

_____ keys work with primary keys to properly implement relationships in the relational model.

Foreign

Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the _____ relationship.

M:N

_____ relationships occur when there are multiple relationship paths between related entities.

Redundant

A total completeness constraint is represented by _____.

a double horizontal line under a circle

In the context of total completeness, in a(n) _____, every supertype occurrence is a member of only one subtype.

disjoint constraint

The extended entity relationship model (EERM) is sometimes referred to as the _____.

enhanced entity relationship model

A primary key's main function is to uniquely identify a(n) _____ within a table.

entity instance or row

The property of _____ enables an entity subtype to inherit the attributes and relationships of the supertype.

inheritance

A specialization hierarchy can have _____ level(s) of supertype/subtype relationships.

many

A _____ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.

natural

Surrogate primary keys are especially helpful when there is no _____ key.

natural

If one exists, a data modeler uses a _____ as the primary key of the entity being modeled.

natural identifier

The "_____" characteristic of a primary key states that the primary key should not have embedded semantic meaning.

nonintelligent

When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when _____.

one side is mandatory and the other side is optional

Within a specialization hierarchy, every subtype can have _____ supertype(s) to which it is directly related.

only one

In the context of total completeness, in a(n) _____, every supertype occurrence is a member of at least one subtype.

overlapping constraint

The preferred placement for a foreign key when working with a 1:1 relationship is to _____.

place the foreign key in one of the entities

One important inheritance characteristic is that all entity subtypes inherit their _____ key attribute from their supertype.

primary

The most important characteristic of an entity is its _____ key, used to uniquely identify each entity instance.

primary

The "_____" characteristic of a primary key states that the selected primary key must not be composed of any attribute(s) that might be considered a violation.

security-compliant

According to the "preferably single-attribute" characteristic of a primary key, the primary key:

should have the minimum number of attributes possible.

The _____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).

specialization hierarchy

A _____ is a primary key created by a database designer to simplify the identification of entity instances.

surrogate key

Nonoverlapping subtypes are subtypes that contain a(n) _____ subset of the supertype entity set.

unique

The "_____" characteristic of a primary key states that the primary key must uniquely identify each entity instance, must be able to guarantee unique values, and must not contain nulls.

unique values