Chapter 5

Question 1

Extended entity relationship diagram

Answer 1

result of adding more semantic constructs to the ER model. This model is used to make an EER diagram

Question 2

Disjoint subtype

Answer 2

contain unique subset of supertype entity set.

Question 3

Overlapping subtype

Answer 3

subtypes that contain nonunique subsets of the supertype entity set

Question 4

Completeness constraint

Answer 4

Specifies whether each entity supertype occurrence must also be a member of at least one subtype

Question 5

Partial completeness

Answer 5

(circle over single line) means that not every supertype occurrence is a member of a subtype

Question 6

Total completeness

Answer 6

(circle over double line) every supertype occurrence must be a member of at least one subtype

Question 7

Speialization

Answer 7

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

Question 8

Generalization

Answer 8

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

Question 9

Entity cluster

Answer 9

a virtual entity type used to represent multiple entities and relationships in the ERD

Question 10

Natural key (natural identifier)

Answer 10

real world identifier that uniquely identifies a real world object

Question 11

Surrogate key

Answer 11

Primary key created by the database designer to simplify the identification of entity instances