Question 1

In a ternary relationship, an occurrence of one entity type is associated with exactly three occurrences of another entity type.

Accepted Answer

In a ternary relationship, an occurrence involves associations among three different entity types, not one entity type associated with three occurrences of another entity type.

Question 2

An associative entity is an alternate way of describing a one-to-one binary relationship.

Accepted Answer

An associative entity is used to describe a many-to-many relationship, not a one-to-one binary relationship.

Question 3

In a many-to-many unary relationship an occurrence of one entity type can be associated with many occurrences of another entity type while each occurrence of the second entity type can be associated with only one occurrence of the first.

Accepted Answer

In a many-to-many unary relationship, an occurrence of the entity type can be associated with many occurrences of the same entity type, not another entity type, and it's reciprocal.

Question 4

A dependent entity would be of no use to a business environment if the entity that it depends on is no longer of use.

Accepted Answer

A dependent entity relies on another entity for its functionality or purpose. If the entity it depends on is no longer useful, the dependent entity also becomes obsolete and irrelevant for the business environment.

Question 5

A one-to-one unary relationship involves a single entity type.

Accepted Answer

A one-to-one unary relationship involves a single entity type where only one entity is involved on either side of the relationship.

Question 6

A one-to-one unary relationship associates one occurrence of an entity type with one occurrence of another entity type.

Accepted Answer

A one-to-one unary relationship associates one occurrence of an entity type with another occurrence of the same entity type, not a different one.

Question 7

It is not necessary to have an associative entity describe a many-to-many binary relationship if there is not intersection data.

Accepted Answer

The answer of It is not necessary to have an...

Question 8

In a one-to-many unary relationship an occurrence of one entity type can be associated with many occurrences of the same entity type.

Accepted Answer

In a one-to-many unary relationship, one occurrence of an entity type can be associated with many occurrences of the same entity type.

Question 9

Draw an entity-relationship diagram that describes the following business environment.
Grand Travel Airlines has to keep track of its flight and airplane history. A flight is uniquely identified by the combination of a flight number and a date. In addition, every flight has an actual departure time and an actual arrival time. Every passenger who has flown on Grand Travel has a unique passenger number plus their name, address, and telephone number. For a particular passenger who has taken a particular flight, the company wants to keep track of the fare that she paid for it and the date that she made the reservation for it. Clearly, a passenger may have taken many flights (he must have taken at least one to be in the database) and every flight has had many passengers on it.
A pilot is identified by a unique pilot (or employee) number, a name, date of birth, and date of hire. A flight on a particular date has exactly one pilot. Each pilot has typically flown many flights but a pilot may be new to the company, is in training, and has not flown any flights, yet.
Each airplane has a unique serial number, a model, manufacturer name, passenger capacity, and year built. A flight on a particular date used one airplane. Each airplane has flown on many flights and dates, but a new airplane may not have been used at all, yet.
Grand Travel also wants to maintain data about its airplanes' maintenance history. A maintenance procedure has a unique procedure number, a procedure name, and the frequency with which it is to be performed on every airplane. A maintenance location has a unique location name, plus an address, telephone number, and manager. Grand Travel wants to keep track of which airplane had which maintenance procedure performed at which location. For each such event it wants to know the date of the event and the duration.

Accepted Answer

The answer of Draw an entity-relationship diagram that describes the...

Question 10

A ternary relationship involves three different entity types.

Accepted Answer

A ternary relationship involves three different entity types, and is represented as a diamond shape in an ER diagram.

Question 11

In a one-to-many unary relationship an occurrence of one entity type can be associated with many occurrences of another entity type while each occurrence of the second entity can be associated with only one occurrence of the first.

Accepted Answer

In a one-to-many unary relationship, an occurrence of the entity type can be associated with many occurrences of the same entity type, not another entity type, as it is a relationship within a single entity.

Question 12

An associative entity is an alternate way of describing a many-to-many binary relationship.

Accepted Answer

An associative entity is a table that connects two or more entities, and it is used to represent a many-to-many relationship between them. Therefore, the statement is true.

Question 13

Draw an entity-relationship diagram that describes the following business environment.
Central Zoo wants to maintain information about its animals, the enclosures in which they live, and its zookeepers and the services they perform for the animals. In addition, Central Zoo has a program by which people can be sponsor of animals. Central Zoo wants to track its sponsors, their dependents, and associated data.
Each animal has a unique animal number, species, name (Jumbo, Fred, etc.), gender, country of birth, and weight. Enclosures have a unique enclosure number, type (cage, fenced field, etc.), location, size, and date built. An animal can live in only one enclosure. An enclosure can have several animals in it or it can be currently empty. A zookeeper has a unique employee number, employee name, title, and year hired. Some zookeepers supervise other zookeepers. Every animal has been cared for by at least one and generally many zookeepers; each zookeeper has cared for at least one and generally many animals. Each time a zookeeper performs a specific, significant service for an animal the service type, date, and time are recorded.
A sponsor sponsors at least one and possibly several animals. An animal may have several sponsors or none. A sponsor has a unique sponsor number, a name, address, and telephone number. For each animal that a particular sponsor sponsors, the zoo wants to track the annual sponsorship contribution and renewal date. In addition, Central Zoo wants to keep track of each sponsor's dependents, keeping their name, relationship to the sponsor, and date of birth. A sponsor may have several dependents or none. A dependent is associated with exactly one sponsor.

Accepted Answer

The answer of Draw an entity-relationship diagram that describes the...

Question 14

Intersection data is associated with one of the two entities in a many-to-many relationship.

Accepted Answer

Intersection data is associated with the relationship itself, not with one of the two entities. It is used to store information relevant to the association between the entities in a many-to-many relationship.

Question 15

In a many-to-many unary relationship an occurrence of one entity type can be associated with many occurrences of the same entity type.

Accepted Answer

In a many-to-many unary relationship, one occurrence of an entity type can be associated with many occurrences of the same entity type. For example, in a social media platform, one user can follow many other users, and each user can be followed by many other users.

Question 16

In a many-to-many unary relationship an occurrence of one entity type can be associated with many occurrences of another entity type while each occurrence of the second entity type can be associated with many occurrences of the first.

Accepted Answer

In a many-to-many unary relationship, an occurrence of the entity type can be associated with many occurrences of the same entity type, not another entity type. This relationship is within a single entity type.

Question 17

It is possible to have a many-to-many binary relationship without intersection data.

Accepted Answer

In a many-to-many binary relationship, there can be multiple instances of each entity connected to multiple instances of the other entity. It is possible for the relationship to exist without any additional intersection data, such as attributes or properties.

Quiz 2: Data Modeling