Deck 5: Advanced Data Modeling

Question 1

Implementing nonoverlapping subtypes requires the use of one discriminator attribute for each subtype.

Answer 1

False

Question 2

The relationships depicted within the specialization hierarchy are sometimes described in terms of "is­a"
relationships.

Answer 2

True

Question 3

The entity supertype contains common characteristics,and the entity subtypes each contain their own unique characteristics.

Answer 3

True

Question 4

A subtype contains attributes that are common to all of its supertypes.

Question 5

An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

Question 6

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

Question 7

Disjoint subtypes are subtypes that contain nonunique subsets of the supertype entity set.

Question 8

Specialization is the top-down process of identifying lower-level,more specific entity subtypes from a higher-level entity supertype.

Question 9

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

Question 10

At the implementation level,the supertype and its subtype(s)depicted in the specialization hierarchy maintain a 1:1 relationship.

Question 11

Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set.

Question 12

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

Question 13

Entity subtypes do not inherit the relationships in which the supertype entity participates.

Question 14

The completeness constraint can be partial or total.

Question 15

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

Question 16

Entity supertypes and subtypes are organized in a specialization hierarchy.

Question 17

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.

Question 18

Generalization is based on grouping unique characteristics and relationships of the subtypes.

Question 19

An entity supertype can have disjoint or overlapping entity subtypes.

Question 20

Within a specialization hierarchy,a supertype can exist only within the context of a subtype.

Question 21

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

A)entity
B)subtypes
C)unique
D)nonunique

Question 22

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

A)zero
B)only one
C)one or many
D)many

Question 23

Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness?

A)Subtype sets are unique.
B)Supertype has optional subtypes.
C)Subtype discriminators cannot be null.
D)Subtype does not have a supertype.

Question 24

Some designs use redundant relationships as a way to simplify the design.

Question 25

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

A)Subtype discriminator can be null.
B)Subtype discriminator cannot be null.
C)Each supertype occurrence is a member of only one subtype.
D)Each supertype occurrence is a member of at least one subtype.

Question 26

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

A)subtype discriminator
B)inheritance
C)specialization hierarchy
D)entity supertype

Question 27

is a generic entity type that is related to one or more entity subtypes.

A)A subtype discriminator
B)Inheritance
C)A specialization hierarchy
D)An entity supertype

Question 28

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

A)primary
B)natural
C)foreign
D)surrogate

Question 29

A(n)is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

A)subtype discriminator
B)inheritance discriminator
C)specialization hierarchy
D)entity supertype

Question 30

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

A)Foreign key constraint
B)nonunique constraint
C)overlapping constraint
D)disjoint constraint

Question 31

To model time-variant data,one must create a new entity in an M:N relationship with the original entity.

Question 32

At the implementation level,the supertype and its subtype(s)depicted in a specialization hierarchy maintain a(n)relationship.

A)self-referencing
B)1:1
C)1:M
D)M:N

Question 33

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

A)zero
B)only one
C)one or many
D)many

Question 34

A partial completeness constraint is represented by .

A)a dotted line
B)two dashed lines
C)a single horizontal line under a circle
D)a double horizontal line over a circle

Question 35

Overlapping subtypes are subtypes that contain subsets of the supertype entity set.

A)null
B)exclusive
C)solitary
D)nonunique

Question 36

A design trap occurs when a relationship is improperly or incompletely identified and is therefore represented in a way that is not consistent with the real world.

Question 37

A total completeness constraint is represented by .

A)a smaller circle inside a bigger circle
B)a rhombus inside a circle
C)a double horizontal line under a circle
D)a single horizontal line above a circle

Question 38

The default comparison condition for the subtype discriminator attribute is the comparison.

A)nonequality
B)less than
C)greater than
D)equality

Question 39

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

A)enclosed entity relationship model
B)enhanced entity relationship model
C)entity clustering relationship model
D)extended entity relationship diagram

Question 40

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

A)subtype discriminator
B)inheritance
C)specialization hierarchy
D)entity supertype

Question 41

An entity cluster is formed by combining multiple interrelated entities into .

A)a single abstract entity object
B)multiple abstract entity objects
C)a single entity object
D)multiple entity objects

Question 42

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

A)foreign key
B)combination key
C)surrogate key
D)natural identifier

Question 43

data refer to data whose values change over time and for which one must keep a history of the data changes.

A)Time-sensitive
B)Time-variant
C)Historical
D)Change-based

Question 44

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.

A)unique values
B)nonintelligent
C)preferably single-attribute
D)security-complaint

Question 45

According to the "preferably single­attribute" characteristic of a primary key,the primary key:

A)must be able to guarantee unique attribute values.
B)should have the minimum number of attributes possible.
C)should have embedded semantic meaning associated with each attribute.
D)must be composed of attributes that are free from security risks or violations.

Question 46

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

A)Composite key
B)compound key
C)natural key
D)surrogate key

Question 47

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.

A)unique values
B)nonintelligent
C)preferably single-attribute
D)security-compliant

Question 48

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

A)primary
B)natural
C)foreign
D)composite

Question 49

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

A)use the same primary key for both entities
B)create a bridge entity
C)place the foreign key in one for the entities
D)place the surrogate key in both entities

Question 50

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

A)Unique constraint
B)disjoint constraint
C)overlapping constraint
D)foreign key constraint

Question 51

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

A)primary
B)natural
C)foreign
D)surrogate

Question 52

is the bottom-up process of identifying a higher-level,more generic entity supertype from lower-level entity subtypes.

A)Specialization
B)Generalization
C)Normalization
D)Total completeness

Question 53

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

A)unique values
B)nonintelligent
C)preferably single-attribute
D)security-compliant

Question 54

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

A)attribute
B)entity instance or row
C)entity subtype
D)natural key or identifier

Question 55

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

A)0:1
B)1:1
C)1:M
D)M:N

Question 56

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

A)primary
B)natural
C)foreign
D)surrogate

Question 57

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

A)Foreign
B)Composite
C)Natural
D)Surrogate

Question 58

A occurs when there is 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)surrogate primary key
B)time-variant data
C)design trap
D)fan trap

Question 59

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 .

A)one side is mandatory and the other sides is optional
B)one side participates in another relationship
C)both sides are optional
D)both sides are mandatory

Question 60

The purpose of a(n)is to simplify an entity-relationship diagram (ERD)and thus enhance its readability.

A)Entity constraint
B)entity cluster
C)entity interface
D)entity discriminator

Question 61

From a data modeling point of view,data refer to data whose values change over time and for which one must keep a history of the data changes.

Question 62

Disjoint subtypes are also known as subtypes.

Question 63

completeness means that every supertype occurrence must be a member of at least one subtype.

Question 64

While using a surrogate key,one must ensure that the candidate key of the entity in question performs properly through the use of the " " and "not null" constraints.

Question 65

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

A)Redundant
B)Duplicated
C)Time-variant
D)Supertype

Question 66

The is the result of adding more semantic constructs to the original entity relationship (ER)model.

Question 67

Composite keys are useful as identifiers of weak entities,where the weak entity has a strong relationship with the parent entity.

Question 68

Composite primary keys are particularly useful as identifiers of composite entities,where each primary key combination is allowed in the M:N relationship.

Question 69

An entity cluster is considered "virtual" or " " in the sense that it is not actually an entity in the final ERD.

Question 70

A weak-entity in a strong identifying relationship with a parent entity is normally used to represent a(n)that is represented in the data model as two separate entities.

Question 71

A(n) occurs when a relationship is improperly or incompletely identified and is therefore represented in a way that is not consistent with the real world.

Question 72

completeness means that not every supertype occurrence is a member of a subtype.

Question 73

Usually,a data modeler uses a natural identifier as the of the entity being modeled,assuming that the entity has a natural identifier.

Question 74

One practical advantage of a(n)key is that because it has no intrinsic meaning,values for it can be generated by the DBMS to ensure that unique values are always provided.

Question 75

What do specialization hierarchies do?

Question 76

The specifies whether each entity supertype occurrence must also be a member of at least one subtype.

Question 77

Specialization is based on grouping characteristics and relationships of the subtypes.

Question 78

Subtypes that contain nonunique subsets of the supertype entity set are known as subtypes.

Question 79

The main concern with redundant relationships is that they remain across the model.

Question 80

Unique values can be better managed when they are ,because the database can use internal routines to implement a counter-style attribute that automatically increments values with the addition of each new row.