Entity Relationship Model

Question 1

Expressed in terms of entities in the business environment, the relationship (or associations) among those entities, and the attributes (or properties) of both the entities and their relationships

Answer 1

Entity-Relationship Model

Question 2

Detailed, logical representation of the data for an organization or for a business area

Answer 2

Entity-Relationship Model

Question 3

is a graphical representation of an E-R Model

Answer 3

E-R Diagram

Question 4

Basic Symbols

A person, place, object, event, or concept in the user environment about which the organization wishes to maintain data (NOUN)

Answer 4

Entity

Question 5

Naming and Defining Entity Types

Answer 5

Singular Noun
Specific to organization
Precise

Question 6

What Should an Entity Be?

Answer 6

• An object that will have many instances in the database
• An object that will be composed of multiple attributes
• An object that we are trying to model

Question 7

Entity Types

Answer 7

• Weak
• Strong

Question 8

An entity that exists independently of other entity types

Answer 8

Strong Entity

Question 9

An entity type whose existence depends on some other entity
type

Answer 9

Weak Entity

Question 10

The relationship between weak entity type and its owner

Answer 10

Identifying Relationship

Question 11

Property or characteristic of an entity type that is of interest to the organization

Answer 11

Attributes

Question 12

An attribute of an entity that must have a value for each entity instance

Answer 12

Required Attribute

Question 13

An attribute of an entity that may not have a value for every entity instance

Answer 13

Optional Attribute

Question 14

An attribute that cannot be broken down into smaller components

Answer 14

Simple (or atomic) attribute

Question 15

An attribute that can be broken down into components parts

Answer 15

Composite attribute

Question 16

An attribute that may take on more than one value for a given entity instance

Answer 16

Multivalued attribute

Question 17

attributes hold a single value for each record.

Answer 17

Single valued attribute

Question 18

are physically stored in the database.

Answer 18

Stored Attribute

Question 19

whose values can be calculated from related attribute values

Answer 19

Derived Attribute

Question 20

An attribute (or combination of attributes) that uniquely identifies individual instances of an entity type

Answer 20

Identifier Attribute

Question 21

Association representing an interaction among the
instances of one or more entity types that is of interest to the organization
Has a verb phrase name – present tense

Answer 21

Relationship

Question 22

A meaningful association between (or among) entity types

Answer 22

Relationship Type

Question 23

An association between (or among) entity instances where each relationship instance includes exactly one entity from each participating entity type

Answer 23

Relationship Instance

Question 24

may be associated with many-to-many (or one-to-one) relationship, as well as with an entity

Answer 24

Attributes

Question 25

An entity type that associates the instances of one or more entity types

Answer 25

Associative Entity

Question 26

involves a rectangle with a diamond inside.

Answer 26

Associative Entity

Question 27

Each entity in the relationship will have exactly one related entity

Answer 27

One-to-One

Question 28

An entity on one side of the relationship can have many related entities, but an entity on the other side will have a maximum of one related entity

Answer 28

one-to-many

Question 29

A relationship between the instances of a single entity type

Answer 29

Unary Relationship

Question 30

Entities on both sides of the relationship can have many related entities on the other side

Answer 30

many-to-many

Question 31

The number of entity types that participate in a relationship

Answer 31

Degree

Question 32

A relationship between the instances of two entity types

Answer 32

Binary Relationship

Question 33

A simultaneous relationship among the instances of three entity types

Answer 33

Ternary Relationship

Question 34

The maximum number of instances of one entity that may be associated with each instance of another entity

Answer 34

Maximum Cardinality

Question 35

The minimum number of instances of one entity that may be associated with each instance of another entity

Answer 35

Minimum Cardinality

Question 36

Specifies the number of instances of one entity that can (or must) be associated with each instance of another entity

Answer 36

Cardinality Constraints