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