Ch. 2

Question 1

Entity-relationship model (e-r model)

Answer 1

Detailed, logical representation of the data for an organization or for a business area. The E-R model is expressed in terms of entities in the business environment, the relationships (or associations) among those entities, and the attributes (or properties) of both the entities and their relationships.

Question 2

entity-relationship diagram

Answer 2

graphical representation of an E-R model.

Question 3

Business rule

Answer 3

A statement that defines or constrains some aspect of the business. It is intended to assert business structure or to control or influence the behavior of the business.

Thoroughly capturing and structuring business rules, then enforcing them through database technologies, helps ensure that information systems work right and that users of the information understand what they enter and see.

Question 4

Term

Answer 4

A word or phrase that has a specific meaning for the business.

Examples of terms are course, section, rental car, flight, reservation, and passenger.

Terms are often the key words used to form data names.

Question 5

Fact

Answer 5

An association between 2 or more terms

A fact is documented as a simple declarative statement that relates terms.

Question 6

entity

Answer 6

A person, a place, an object, an event, or a concept in the user environment about which the organization wishes to maintain data.

Question 7

Entity type

Answer 7

A collection of entities that share common properties or characteristics. Each entity type in an E-R model is given a name. Because the name represents a collection (or set) of items, it is always singular. We use capital letters for names of entity type(s).

In an E-R diagram, the entity name is placed inside the box representing the entity type.

Question 8

entity instance

Answer 8

Single occurrence of an entity type