Chapter 5

The implementation of disjoint subtypes is based on the value of the ____.____ attribute in the supertype. a. inheritance factor b. primary key attribute c. foreign key attribute d. subtype discriminator

d. subtype discriminator

A ________ is especially helpful when there is no natural key. a. composite primary key b. shared primary key c. derived primary key d. surrogate primary key

d. surrogate primary key

In a specialization hierarchy constraint scenario with total disjoint constraint, ____.____. a. subtype sets are not unique b. an entity supertype has optional subtypes c. supertype occurrences can be members of many subtypes d. the subtype discriminator cannot be null

d. the subtype discriminator cannot be null

In an aviation company's data model, a PILOT entity is a(n) ____.____ of the EMPLOYEE entity. a. subtype b. attribute c. cluster d. domain

subtype

Entity supertypes and subtypes are organized in a(n) ____.____. a. linear hierarchy b. generalization hierarchy c. specialization hierarchy d. overlapping hierarchy

Specialization Hierarchy

At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a ____.____. a. 1:1 relationship b. 1:M relationship c. M:N relationship d. 0:1 relationship

a. 1:1 relationship

Which of the following is true of entity supertypes and subtypes? a. A supertype contains those attributes that are common to all of its subtypes. b. A subtype cannot inherit the attributes and relationships of a supertype. c. A subtype shares characteristics with other entity subtypes. d. A supertype is a virtual entity type used to represent mulitple entities and relationships.

a. A supertype contains those attributes that are common to all of its subtypes.

Which of the following types of primary key is useful to represent M:N relationships? a. Composite key b. Surrogate key c. Foreign key d. Secondary key

a. Composite key

________ occur when there are multiple relationship paths between related entities. a. Redundant relationships b. Joined relationships c. Identifying relationships d. Shared relationships

a. Redundant relationships

The extended entity relationship model is also known as ____.____. a. enhanced entity relationship model b. redesigned entity relationship model c. complete entity relationship model

a. enhanced entity relationship model

A ________ refers to a real-world, generally accepted identifier used to distinguish real-world objects. a. secondary key b. natural key c. candidate key d. derived key

b. natural key

____.____ is the bottom-up process of identifying a higher-level, more generic entity supertype from lower-level entity subtypes. a. Clustering b. Completeness c. Generalization d. Discrimination

c. Generalization

In specialization hierarchies with multiple levels of supertype/subtypes, ____.____. a. a higher-level entity supertype can be identified from lower-level subtypes through a bottom-up process b. a lower-level subtype shares common characteristics with other subtypes c. a lower-level subtype inherits all of the attributes and relationships from all of its upper-level supertypes d. a higher-level entity supertype is created by grouping multiple entities into a single, abstract entity

c. a lower-level subtype inherits all of the attributes and relationships from all of its upper-level supertypes

Which of the following is the most preferred data type for a primary key? a. Text b. Boolean c. Array d. Numeric

d. Numeric

An entity subtype ____.____. a. contains its own unique characteristics b. is an abstract entity c. represents multiple interrelated entities d. is a generic entity type

A: Contains its own unique characteristics

The property of ____.____ enables an entity subtype to gain the attributes and relationships of the supertype. a. generalization b. inheritance c. uniqueness d. specialization

B: Inheritance

In modeling terms, the ________ contains common characteristics. a. entity subtype b. base entity c. higher entity d. entity supertype

Entity Supertype

1. The ________ adds support for entity supertypes, subtypes, and entity clustering. a. hierarchical entity model b. object-oriented model c. relational model d. extended entity relationship model

Extended Entity Relationship Model

In a specialization hierarchy constraint scenario with partial disjoint constraint, ____.____. a. an entity supertype has optional subtypes b. the subtype discriminator should not be null c. each supertype occurrence is a member of only one subtype d. subtype sets are not unique

a. an entity supertype has optional subtypes

A weak entity in a strong identifying relationship with a parent entity is normally used to represent ___.____. a. an object that can exist in the model without relating to other objects in a strong identifying relationship b. a real-world object that is existent independent of another real-world object c. a virtual entity that is used to represent multiple entities and relationships d. a real-world object that is represented in the data model as two separate entities in a strong identifying relationship

a. an object that can exist in the model without relating to other objects in a strong identifying relationship

In an entity relationship diagram (ERD) that uses entity clusters, it is common to ___._____. a. avoid the use of entity names b. include dummy entities c. describe the purpose of each entity d. avoid the display of attributes

a. avoid the use of entity names

Every subtype can ____.____. a. have only one supertype to which it is related b. have nulls in attributes c. avoid inheritance of attributes d. have attributes that are common to other subtypes

a. have only one supertype to which it is related

Subtypes that contain nonunique subsets of the supertype entity set are known as ____.____. a. overlapping subtypes b. joined subtypes c. complex subtypes d. shared subtypes

a. overlapping subtypes

Arguably, the most important characteristic of an entity is its ________. a. primary key b. relationships c. attributes d. name

a. primary key

The purpose of an entity cluster is to ________. a. simplify the entity relationship diagram (ERD) b. provide key attributes of the combined entities c. define physical database storage for related entities d. group related entities into a single table

a. simplify the entity relationship diagram (ERD)

A(n) ____.____ is the attribute in the supertype entity that determines to which subtype each supertype occurrence is related. a. subtype discriminator b. supertype selector c. inheritance instance d. inheritance key

a. subtype discriminator

A ________ has no meaning in the user's environment. a. surrogate key b. composite key c. foreign key d. virtual key

a. surrogate key

Which of the following is an example of time-variant data? a. A person's Social Security number b. A person's bank account balance c. A manufactured part's serial number d. An employee's date of birth

b. A person's bank account balance

Which of the following is the default comparison condition for the subtype discriminator attribute? a. Three-way comparison b. Equality comparison c. Identity comparison d. Synctactical comparison

b. Equality comparison

In a specialization hierarchy constraint scenario with partial overlapping constraint, ____.____. a. subtype sets are unique b. an entity supertype has optional subtypes c. each supertype occurrence is a member of only one subtype d. the subtype discriminator cannot be null

b. an entity supertype has optional subtypes

In an organization's data model, employees are grouped to ____.____. a. create multiple relationship paths between all the employee types b. avoid nulls when some employees have characteristics that are not shared by other employees c. enable an employee type to participate in relationships that are common to several employee types d. allows the data model to capture additional semantic content

b. avoid nulls when some employees have characteristics that are not shared by other employees

A ________ is used as an identifier for weak entities in a strong identifying relationship with a parent entity. a. virtual key b. composite primary key c. candidate key d. surrogate primary key

b. composite primary key

The specialization hierarchy provides a means to ____.____. a. prevent attribute inheritance b. define a subtype discriminator c. allows subtype sets to be unique in all scenarios d. avoid optional subtypes

b. define a subtype discriminator

Subtypes that contain a unique subset of the supertype entity set are known as ________. a. exclusive subtypes b. disjoint subtypes c. isolated subtypes d. unique subtypes

b. disjoint subtypes

A(n) ____.____ is a "virtual" entity type used to represent multiple entities and relationships in the ERD. a. domain segment b. entity cluster c. domain group d. entity section

b. entity cluster

In an existence-dependent relationship, the primary key of the dependent entity is a ____.____. a. derived key b. foreign key c. composite key d. surrogate key

b. foreign key

One of the characteristics of a primary key is that ________. a. it is subject to change over time b. it uniquely identifies each entity instance c. it describes the entity in detail d. it can have embedded semantic meaning other than to uniquely identify each entity instance

b. it uniquely identifies each entity instance

The extended entity relationship model (EERM) supports ________ where a subtype can have multiple parents (supertypes). a. domain networks b. specialization lattices c. relationship webs d. subtype categories

b. specialization lattices

When defining a 1:1 relationship where one side of the relationship is mandatory and one is optional, ________. a. the foreign key should be made optional b. the foreign key should be placed in the table that defines the optional entity c. the model should be revised to ensure that the two entities do not belong together d. the foreign key should be placed in both entities in the relation

b. the foreign key should be placed in the table that defines the optional entity

When defining a 1:1 relationship where both sides of the relationship are mandatory, ____.____. a. the foreign key that causes the fewest nulls should be selected b. the model should be revised to ensure that the two entities do not belong together c. the foreign key should be placed in the entity in which the relationship role in not played d. the foreign key should be placed in both entities in the relationship

b. the model should be revised to ensure that the two entities do not belong together

________ refer to data whose values change in the future and for which you must keep a history of the data changes. a. Historic data b. Event-driven data c. Time-variant data d. Closed data

c. Time-variant data

The ____.____ specifies whether each entity supertype occurrence must also be a member of at least one subtype. a. uniqueness factor b. attribute inheritance c. completeness constraint d. specialization hierarchy

c. completeness constraint

A(n) ____.____ occurs when a relationship is improperly or incompletely identified and, therefore, is represented in a way that is not consistent with the real world. a. relationship web b. infinite loop c. design trap d. deadlock

c. design trap

A(n) ________ occurs when you have one entity in two 1:M relationships to other entities, thus producing an association among the other entities that is not expressed in the model. a. relationship web b. impasse c. fan trap d. gridlock

c. fan trap

One important inheritance characteristic is that all entity subtypes inherit their _____.___ from their supertype. a. subtype discriminators b. candidate keys c. primary key attributes d. indexes

c. primary key attributes

A primary key's function is to ____.____. a. enhance readability of an entity relationship diagram (ERD) b. provide a description of the entity c. uniquely identify an entity instance or row within a table d. represent multiple entities and their relationships

c. uniquely identify an entity instance or row within a table

A specialization hierarchy reflects the ____.____. a. grouping of common characteristics and relationships of subtypes b. bottom-up process of identifying a higher-level entity supertype from lower-level subtype c. virtual entities used to represent multiple entities and relationships d. 1:1 relationship between an entity supertype and its subtypes

d. 1:1 relationship between an entity supertype and its subtypes

________ are used to implement relationships among entities. a. Entity supertypes b. Subtype discriminators c. Partial completeness constraints d. Primary keys and foreign keys

d. Primary keys and foreign keys

____.____ is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype. a. Generalization b. Clustering c. Overlapping d. Specialization

d. Specialization

In MS Visio, the completeness constraint is based on the ____.____. a. item number b. entity name c. inheritance factor d. category shape

d. category shape