Database Chapter 2

In the figure below, which of the following is true?

A person can marry at most one person.

Which of the following criteria should be considered when selecting an identifier?

All of the above: choose an identifier that will not be null choose an identifier that doesn't have large composite attributes choose an identifier that is stable

In the following diagram, which of the below answers is true?

Both A and C: Each patient has one or more patient histories. Each patient history belongs to one and only one patient.

In the following diagram, which answer is true?

Each employee can supervise one to many employees.

Which of the following is NOT a good characteristic of a data name?

Relates to a technical characteristic of the system

In the figure below, which attribute is multivalued?

Skill

An entity name should be all of the following EXCEPT:

as short as possible

An entity that associates the instances of one or more entity types and contains attributes specific to the relationships is called a(n):

associative entity

A person's name, birthday, and social security number are all examples of:

attributes

The number of entity types that participate in a relationship is called the:

degree

Customers, cars, and parts are examples of:

entities

An attribute that must have a value for every entity (or relationship) instance is a(n):

required attribute

For the relationship represented in the figure below, which of the following is true?

A department can have more than one employee.

Which of the following conditions should exist if an associative entity is to be created?

All of the above: All the relationships for the participating entities are many-to-many The new associative entity has independent meaning The new associative entity participates in independent relationships

Which of the following should be considered when selecting an identifier?

All of the above: choose an identifier that will not be null choose an identifier that doesn't have large composite attributes choose an identifier that is stable

In the following diagram, which is true?

All of the above: it depicts a unary relationship it depicts a many-to-many relationship there is an associative entity

The common types of entities are:

All of the above: strong entities weak entities associative entities

A property or characteristic of an entity type that is of interest to the organization is called a(n):

attribute

An attribute that uniquely identifies an entity and consists of a composite attribute is called a(n):

composite identifier

An attribute that can be calculated from related attribute values is called a(n) _____ attribute.

derived

The total quiz points for a student for an entire semester is a(n) _____ attribute.

derived

The logical representation of an organization's data is called a(n):

entity-relationship model

A student can attend five classes, each with a different professor. Each professor has 30 students. The relationship of student to professors is a _____ relationship.

many-to-many

In an E-R diagram, there are _____ business rule(s) for every relationship.

two

An entity type whose existence depends on another entity type is called a _____ entity.

weak

A good data definition will describe all of the characteristics of a data object EXCEPT:

who can delete the data