Chapter 3: Enhanced Entity Relationship Model

Question 1

A subgrouping of the entities in an
entity type that is meaningful to
the organization and that shares
common attributes or relationships
distinct from other subgrouping

Answer 1

subtype

Question 2

A generic entity type that has a
relationship with one or more
subtypes.

Answer 2

Supertype

Question 3

What is the symbol that indicates that the entity is a subtype to a super type?

Answer 3

U shape connected to a circle

Question 4

A property by which subtype
entities inherit values of all
attributes and instances of all
relationships of their supertype.

Answer 4

Attribute Inheritance

Question 5

If a subtype has an instance, the instance is also an instance of the super type (T or F)

Answer 5

True

Question 6

What situations would you consider to use a supertype/subtype relationship

Answer 6

1. When attributes apply to some and not all instances of an entity
2. When a subtype participate in a relationship unique to that subtype

Question 7

From the two approaches of creating subtypes/supertype relationships, what approach does generalization and specialization take?

Answer 7

Generalization: Bottom-up
Specialization: Top-down

Question 8

is the process of defining a more general entity type from a set of more specialized entity types

Answer 8

Generalization

Question 9

Addresses whether an instance of a supertype must also be a member of at least one subtype.

Answer 9

Completeness Constraint

Question 10

A rule that specifies that each
entity instance of a supertype must
be a member of some subtype in
the relationship

Answer 10

Total Specialization Rule

Question 11

A rule that specifies that an entity
instance of a supertype is allowed
not to belong to any subtype.

Answer 11

Partial Specialization Rule

Question 12

Completeness Constraint: What is the symbol to indicate that there is a total specialization rule?

Answer 12

Double line connecting from the supertype to the circle

Question 13

Completeness Constraint: What symbol is used to indicate a partial specialization rule?

Answer 13

Single line connected from the supertype to the circle

Question 14

A constraint that addresses
whether an instance of a supertype
may simultaneously be a member
of two (or more) subtypes

Answer 14

disjointness constraint

Question 15

A rule that specifies that an
instance of a supertype may not
simultaneously be a member of
two (or more) subtypes.

Answer 15

Disjoint Rule

Question 16

A rule that specifies that an
instance of a supertype may
simultaneously be a member of
two (or more) subtypes.

Answer 16

Overlap rule

Question 17

Disjointness constraint: what symbol is used to represent disjoint and overlap rule?

Answer 17

A d or o inside the circle

Question 18

An attribute of a supertype whose
values determine the target
subtype or subtypes.

Answer 18

Subtype discriminator

Question 19

Subtype Discriminator: What type of attribute is used with a disjoint rule?

Answer 19

a simple attribute

Question 20

Subtype Discriminator: What type of attribute is used for an overlap subtype?

Answer 20

a composite attribute

Question 21

A supertype/subtype hierarchy is a hierarchical arrangement of
supertypes and subtypes, where

Answer 21

a subtype has only one supertype

Question 22

The entity type at the top of the hierarchy is also called?

Answer 22

root

Question 23

A subtype only inherits the attributes from its immediate supertype (T or F)

Answer 23

False. The subtype inherits the attiributes of supertypes until it reaches the root

Question 24

is an iterative approach to breaking a system down into related components so that each component can be redesigned by
itself without destroying the connections with other components

Answer 24

Functional decomposition

Question 25

A set of one or more entity types
and associated relationships
grouped into a single abstract
entity type.

Answer 25

Entity Cluster

Question 26

An entity cluster can be made from combining strong and weak entities (T or F)

Answer 26

true

Question 27

is a generic or template data model that can be reused as
a starting point for a data modeling project

Answer 27

Universal data model

Question 28

Universal Data Model: A universal data model is the right model for your organization (T or F)

Answer 28

False. It is only a good starting point

Question 29

Universal Data Model: What are the advantages of using UDMs

Answer 29

1. evolved from cumulative experience
2. takes less time and costs
3. less likely to miss important components
4. easier to evolve
5. good starting point
6. easier to read
7. extensive use of supertype/subtype relationships promote reusing data and holistic view
8. extensive use of many to many relationships and associative entities makes it flexible
9. compatibility with vendor products
10. easier to share data with other organizations

Question 30

Universal Data Model: In general, business rules embedded in the purchased data cover all possible circumstances (T or F)

Answer 30

True

Question 31

Universal Data Model:can find outliers, identify shifts in data distribution over time, and identify other
phenomena

Answer 31

Profiling

Question 32

Universal Data Model: What is the most important challenge in customizing data models

Answer 32

Determining the business rules