Quiz 2 - Ch 5

Question 1

Result of adding more semantic constructs to the original entity relationship (ER) model: E….. E….. R….. M…..

Answer 1

Extended Entity Relationship Model

Question 2

Generic entity type related to one or more entity subtypes: E…. S……

Answer 2

Entity Supertype

Question 3

Contains unique characteristics of each entity subtype: E….. S……

Answer 3

Entity subtype

Question 4

Entity Supertypes and Subtypes: There must be d……, i………kinds of the e…. in the user’s environment

Answer 4

different/ identifiable/ entity

Question 5

Entity Supertypes and Subtypes: The different kinds of instances should each have one or more a……. that are u…… to that kind of instance

Answer 5

attribute / unique

Question 6

Entity supertypes and subtypes are organized in a s…………….. h…………

Answer 6

specialization hierarchy

Question 7

S………….. h………….. depicts arrangement of higher-level entity supertypes and lower-level entity subtypes

Answer 7

specialization hierarchy

Question 8

Relationships are described in terms of “ i….” relationships

Answer 8

“is-a”

Question 9

S……… exists within the context of a s………

Answer 9

Subtype / supertype

Question 10

Every s………. has one s……….. to which it is directly related

Answer 10

Subtype / supertype

Question 11

S……….. can have many s…….

Answer 11

Supertype/ subtype

Question 12

Specialaization Hierarchy provides the means to:

• Support a……….. i…………
• Define a special s……… a……… known as the s……….. d……..
• Define d…../o… constrains and c……/p…….. constrains

Answer 12

Support attribute inheritance
Define a special supertype attribute known as the subtype discriminator
Define disjoint/overlapping constraints and complete/partial constraints

Question 13

Enables an entity subtype to inherit attributes and relationships of the supertype: I………….

Answer 13

Inheritance

Question 14

All entity subtypes i………their primary key attribute from their supertype

Answer 14

inherite

Question 15

At the implementation level, supertype and its subtype(s) maintain a …. relationship

Answer 15

1:1

Question 16

Entity subtypes i……. a… relationships in which supertype entity participates

Answer 16

inherit all

Question 17

Lower-level s……… i……….. all attributes and relationships from its upper-level s……….

Answer 17

subtypes inherit / supertype

Question 18

Attribute in the supertype entity that determines to which entity subtype the supertype occurrence is related : S…………. D………..

Answer 18

Subtype Discriminator

Question 19

Contain a unique subset of the supertype entity set : D………… S………….

Answer 19

Disjoint subtypes

Question 20

Known as nonoverlapping subtypes: D………. s……….

Answer 20

disjoint subtypes

Question 21

Contain nonunique subsets of the supertype entity set : O………. s…………

Answer 21

Overlapping subtypes

Question 22

Implementation is based on the value of the subtype discriminator attribute in the supertype: D………. s……….

Answer 22

Disjoint subtype

Question 23

Implementation requires the use of one discriminator attribute for each subtype : O………… s……………

Answer 23

Overlapping subtypes

Question 24

Specifies whether each supertype occurrence must also be a member of at least one subtype: C………….. C………..

Answer 24

Completeness Constraint

Question 25

P………. c……..: Not every supertype occurrence is a member of a subtype

Answer 25

Partial Completeness

Question 26

T……….. c………..: Every supertype occurrence must be a member of at least one subtype.

Answer 26

Total completeness

Question 27

Subtype discriminator can be null for p…… c……….

Answer 27

partial completeness

Question 28

Top-down process : S……….

Answer 28

Specialization

Question 29

Identifies lower-level, more specific entity subtypes from a higher-level entity supertype: S………..

Answer 29

Specialization

Question 30

Based on grouping unique characteristics and relationships of the subtypes S………….

Answer 30

Specialization

Question 31

Bottom-up process: G………..

Answer 31

Generalization

Question 32

Identifies a higher-level, more generic entity supertype from lower-level entity subtypes: G……..

Answer 32

Generalization

Question 33

Based on grouping common characteristics and relationships of the subtypes: G………….

Answer 33

Generalization

Question 34

Virtual entity type used to represent multiple entities and relationships in ERD: E……….. C…………

Answer 34

Entity Cluster

Question 35

Avoid the display of attributes (no key attributes) to eliminate complications that result when the inheritance rules change : E……….. C…………

Answer 35

Entity Cluster

Question 36

Real-world identifier used to uniquely identify real-world objects: N…….. k……….

Answer 36

natural keys or natural identifier

Question 37

Desirable Primary Key Characteristics
Non I................
No c.........over time
Preferably s........- a.......
Preferably n..........
S.........-c...........

Answer 37

Non Intelligent
No change over time
Preferably single- attribute
Preferably numeric
Security-compliant

Question 38

The PK should not have embedded semantic meaning other than to uniquely identify each entity instance: Non I…………

Answer 38

Non intelligent

Question 39

The selected primary key must not be composed of any attribute that might be considerd a security risk or violation: S………… c………..

Answer 39

security compliance

Question 40

Each primary key combination is allowed once in (…:..) relationship

Answer 40

M:N

Question 41

Primary key used to simplify the identification of entity instances : S………… K…………..

Answer 41

Surrogate Keys

Question 42

Surrogate Keys are useful when:
There is no n………. k………..
Selected candidate key has embedded s………. contents or is too l………

Answer 42

There is no natural key

Selected candidate key has embedded semantic contents or is too long

Question 43

Require ensuring that the candidate key of entity in question performs properly: S………. K…..

Answer 43

Surrogate Keys

Question 44

Use unique index and not null constraints : s……….. K………

Answer 44

Surrogate Keys

Question 45

Data whose values change over time and for which a history of the data changes must be retained: t…….-V………….. D……….

Answer 45

Time-variant data

Question 46

Time-variant data Requires creating a new entity in a ( .. : ..) relationship with the original entity

Answer 46

1:M

Question 47

Occurs when a relationship is improperly or incompletely identified: D……….. t……….

Answer 47

Design trap

Question 48

Represented in a way not consistent with the real world : D……… t………….

Answer 48

Design trap

Question 49

Occurs when one entity is in two 1:M relationships to other entities: F………. t…………

Answer 49

Fan trap

Question 50

Produces an association among other entities not expressed in the model: F………. t…………

Answer 50

Fan trap

Question 51

Occur when there are multiple relationship paths between related entities: R…………. R………….

Answer 51

Redundant Relationships

Question 52

The relationship could be safely deleted with out losing any information generation capabilities in the model: : R…………. R………….

Answer 52

Redundant Relationships