Ch. 5 Quiz

A total completeness constraint is represented by a _____. - single horizontal line above a circle - double horizontal line under a circle - smaller circle inside a bigger circle - rhombus inside a circle

double horizontal line under a circle

A(n) ______ is a generic entity type that is related to one or more entity subtypes. - subtype discriminator - inheritance - entity supertype - specialization hierarchy

entity supertype

The default comparison condition for the subtype discriminator attribute is the _____ comparison. - equality - greater than - less than - nonequality

equality

In specialization hierarchies with multiple levels of supertype and subtypes, a lower-level subtype can inherit only a few of the attributes and relationships from its upper-level supertypes. - False - True

false

Structural dependence exists when it is possible to make changes in the file structure without affecting the application program's ability to access the data. - True - False

false

The function of the primary key is to describe an entity. - False - True

false

The property of a subtype discriminator enables an entity supertype to inherit the attributes and relationships of the subtype. - True - False

false

______ is the bottom-up process of identifying a higher-level, more generic entity supertype from lower-level entity subtypes. - Generalization - Specialization -Total completeness - Normalization

generalization

The property of _______ enables an entity subtype to inherit the attributes and relationships of the supertype. - inheritance - entity supertype - subtype discriminator - specialization hierarchy

inheritance

A ______ key is a real-world, generally accepted identifier used to uniquely identify real-world objects. • foreign • surrogate • natural • primary

natural

If one exists, a data modeler uses a _____ as the primary key of the entity being modeled. - surrogate key - combination key - foreign key - natural identifier

natural identifier

Overlapping subtypes are subtypes that contain _____ subsets of the supertype entity set. - null - nonunique - solitary - exclusive

nonunique

Within a specialization hierarchy, every subtype can have supertype(s) to which it is directly related. - one or many - many - only one - zero

only one

In the context of total completeness, in a(n) ________, every supertype occurrence is a member of at least one subtype. - foreign key constraint - disjoint constraint - unique constraint - overlapping constraint

overlapping constraint

The most important characteristic of an entity is its _____ key, used to uniquely identify each entity instance. - primary - surrogate - foreign - natural

primary

According to the "preferably single-attribute" characteristic of a primary key, the primary key: - must be able to guarantee unique attribute values. - should have the minimum number of attributes possible. - must be composed of attributes that are free from security risks or violations. - should have embedded semantic meaning associated with each attribute.

should have the minimum number of attributes possible.

A ______ is a primary key created by a database designer to simplify the identification of entity instances. - surrogate key - natural key - compound key - composite key

surrogate key

At the implementation level, the supertype and its subtypes) depicted in the specialization hierarchy maintain a 1:1 relationship. - True - False

true

Entity supertypes and subtypes are organized in a specialization hierarchy. - False - True

true

Implementing overlapping subtypes requires the use of one discriminator attribute for each subtype. - False - True

true

Nonoverlapping subtypes are subtypes that contain a(n) ______ subset of the supertype entity set. - entity - unique - nonunique - subtypes

unique

Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness? - Subtype discriminators cannot be null. - Supertype has optional subtypes. - Subtype does not have a supertype. - Subtype sets are unique.

Supertype has optional subtypes.

An entity cluster is formed by combining multiple interrelated entities into ______. - a single entity object - multiple entity objects - a single abstract entity object - multiple abstract entity objects

a single abstract entity object

A partial completeness constraint is represented by ______. - a dotted line - a double horizontal line over a circle - two dashed lines - a single horizontal line under a circle

a single horizontal line under a circle

The purpose of an entity ______ is to simplify an entity-relationship diagram (ERD) and thus enhance its readability. - interface - discriminator - constraint - cluster

cluster