Chapter 5

Database Processing: Fundamentals,
Design, and Implementation

Fifteenth Edition

Chapter 5

Data Modeling with the

Entity-Relationship Model

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Learning Objectives (1 of 2)

5.1 To understand the two-phase data modeling/database design process

5.2To understand the purpose of the data modeling process

5.3 To understand entity-relationship (E-R) diagrams

5.4To be able to determine entities, attributes, and relationships

5.5 To be able to create entity identifiers

5.6 To be able to determine minimum and maximum cardinalities

5.7To understand variations of the E-R model

5.8 To understand and be able to use ID-dependent and other weak
entities

5.9 To understand and be able to use supertype/subtype entities

5.10To understand and be able to use strong entity relationship patterns

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Learning Objectives (2 of 2)

5.11 To understand and be able to use the ID-dependent association
relationship pattern

5.12 To understand and be able to use the ID-dependent multivalued
attribute relationship pattern

5.13 To understand and be able to use the ID-dependent
archetype/instance relationship pattern.

5.14 To understand and be able to use the line-item pattern

5.15 To understand and be able to use the for-use-by subtype patterns

5.16 To understand and be able to use recursive relationship patterns

5.17 The understand the iterative nature of the data modeling process

5.18 To be able to apply the data modeling process

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The Data Model

• A data model is a plan or blueprint for a database design.

• A data model is more generalized and abstract than a

database design.

• It is easier to change a data model then it is to change a

database design, so it is the appropriate place to work
through conceptual database problems.

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The Data Model similar to…

Architecture model

Clay model

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Design Stages

– Conceptual design (conceptual schema)
– Logical design (logical schema)
– Physical design (physical schema)

• The Entity-Relationship (E-R) modelis a set of graphical

symbols that can be used to visually describe the design.

Multiple Choice

Does the conceptual model correspond to the data model?

• True

• False

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Design Stages

ERD feature

Conceptual

Logical

Physical

Entity/table (name)

Yes

Yes

Yes

Relationship

Yes

Yes

Yes

Column (attribute)

Yes

Yes

Column’s Type

Optional

Yes

Primary Key

Yes

Foreign Key

Yes

Multiple Choice

Does the conceptual model has information about the Primary and foreign key of each table/element?

• True

• False

Multiple Choice

This diagram best the describe the _____ model of the database.

• Conceptual

• Logical

• Physical

Multiple Choice

This diagram best describe the ______model of the database.

• Conceptual

• Logical

• Physical

Multiple Choice

This model is considered____

• Conceptual

• Logical

• Physical

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The Entity-Relationship (E-R) Model

• Versions:

– Original E-R model—by Peter Chen (1976)

– Extended E-R model—later extensions to the Chen

model included subtypes

– Now referred to as the extended E-R model, which is

used in this book when using the term E-R model

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ERD diagrams track

• Entities: something that can be readily identified and that

users want to track

• Attributes describe an entity’s characteristics.
• Relationships between entities

– Max Cardinality

– One-to-One [1:1]
– One-to-Many [1:N]
– Many-to-Many [N:M]

– Min Cardinality

– zero [0] participation in the relationship by the

entity is optional.

– one [1] participation in the relationship by the

entity is mandatory.

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Types of Maximum Cardinality

Multiple Choice

If an employee can work at one company a time and the company can have many employees, then the relationship between entities employee and company is considered ____

• 1 to many

• 1 to 1

• many to many

• none of these

Multiple Choice

The relationship between the entities country and government is _________

• one to many

• one to one

• many to many

• none of these

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Types of Minimum Cardinality

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Combined cardinality

Multiple Choice

Based on this figure___

• Employee might not necessary assigned to a department

• Employee can be assigned to many departments at the same time

• A department might have no employees

• none of these

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Figure 5-2 Variations of Attributes with
E-R Models

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Figure 5-3 Entity Attribute Display in
Data Models

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Crow’s Foot Notation

IE Crow’s Foot Symbol Summary

Symbol

Meaning

Numeric Meaning

Two hash marks on the
relationship line
Mandatory–One

Exactly-One

A hash mark and a crow’s foot
on the relationship line
Mandatory–Many

One or More

A circle and a hash mark on the
relationship line
Optional–One

Zero or one

A circle and a crow’s foot on the
relationship line
Optional–Many

Zero or more

ERD Example

In a library system, Books are written by Authors, published by Publishers, and can be borrowed by
Members. Authors can write many Books, Publishers can publish many Books, and Members can borrow many Books. A Book can only have one Author, one Publisher, and be borrowed by multiple members (not at same time). Each publisher has an assigned salesperson who is dedicated to only one publisher.

Multiple Choice

To create an entity relationship diagram for this system, you would create how many entities/tables?

• 2

• 3

• 4

• 5

Multiple Choice

The relationship between the book and the publisher should be___

• 1 to 1

• 1 to M

• M to M

• No relation

Multiple Choice

The relationship between the salesperson and the publisher should be___

• 1 to 1

• 1 to M

• M to M

• no relation

Library ERD

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