Quiz 2

A recursive relationship is one in which a relationship can exist between the same entity set. A. True B. False

A. True

A superclass can have more than two subclasses. A. True B. False

A. True

According to our convention, entity names are always singular. A. True B. False

A. True

This ERD shows that (choose all the possible answers) A. An app can be downloaded by at most five members. B. No apps have 0 download. C. Every member has downloaded at least one app, some have more than one apps. D. An app can be downloaded by more than 5 members. E. A member can download at most 5 apps.

A., C.

This ERD shows A. A super class with 3 subclasses B. 3 binary relationships C. 1 ternary relationship D. 2 binary relationships and a superclass with its 1 subclass E. a quaternary relationship

B. 3 binary relationships

Entity-Relationship Diagrams are dependent on the hardware or software used for implementation. A. True B. False

B. False

On a superclass/subclass relationship, the participation constraint indicates: A. the maximum number of subclasses participating in the relationship B. whether every member of the superclass belongs to a subclass C. how many levels of subclasses participate in the hierarchy D. if subclasses can participate in relationships with other entities E. the number of subclasses to which a superclass member can belong

B. whether every member of the superclass belongs to a subclass

From the ERD is Question #3, we know that (choose all the correct answers) A. An app can belong to multiple categories. B. A category may not have any apps. C. An app can be developed by one or more developers. D. Some developers may not have developed any apps. E. Every member has downloaded at least one app.

B., C., D., E.

Given the data above, what are the multiplicity constraints on the Subscribes relationship? A. X 0..1 Y 1..1 Z 1..1 B. X 1..* Y 1..* Z 1..1 C. X 1..1 Y 1..* Z 1..1 D. X 1..* Y 1..* Z 1..* E. X 1..* Y 1..* Z 0..1

C. X 1..1 Y 1..* Z 1..1

"App Pro" is a website that provides app download service to its members. Some members has only registered but have never downloaded any apps. Some members have downloaded 1 or more apps. Popular apps have been downloaded by many members, others haven't been downloaded. Given the information above, what are the multiplicity constraints on the Downloads relationship? A. X 0..1 Y 1..1 B. X 0..* Y 1..1 C. X 0..* Y 1..* D. X 0..* Y 0..* E. X 1..* Y 1..*

D. X 0..* Y 0..*