Chapter 3-1 Chapter 3: Data Modeling Introduction An Overview of Databases Steps in Developing a Database Using Resources, Events and Agents Model Normalization.

Chapter 3-1

Chapter 3:Data Modeling

Introduction

An Overview of Databases

Steps in Developing a Database Using Resources, Events and Agents Model

Normalization

Chapter 3-2

Introduction

Uses of a modern AIS

Systematically record data

Provide convenient and useful formats

Easy access to information

Chapter 3-3

What is a Database?

Collection of organized data

Used by many different computer applications

Manipulated by database management systems (DBMS)

Chapter 3-4

Significance of a Database

Critical information

Volume

Distribution

Privacy

Irreplaceable data

Need for accuracy

Internet uses

Chapter 3-5

Data must be stored and organized systematically

Three important concepts: Data hierarchy Record structures Database keys

Storing Data in Databases

Chapter 3-6

Data Hierarchy

Data organization in ascending order:Data fieldRecordFileDatabase

Chapter 3-7

Record Structures

Data fields in each record of a database table

Structure is usually fixed

Example

Chapter 3-8

Database Keys

Primary KeyUnique to each record

Foreign KeysEnable referencing of one or more recordsMatches primary key of related table

Chapter 3-9

Records Combined Into Report

Chapter 3-10

Additional Database Issues

Administration Database Administrator

Documentation Includes a variety of descriptions Structures, Contents, Security Features Data Dictionary Metadata

Chapter 3-11

Data Dictionary Example

Chapter 3-12

Additional Database Issues

Data Integrity Data Integrity controls Designed by database developers

Processing Accuracy and Completeness Transaction controls Ensures accurate transaction processing

Chapter 3-13

Additional Database Issues

Concurrency Concurrency controls Prevent multi-user access at same time

Backup and Security Ability to recreate data Prevent unauthorized access View controls

Chapter 3-14

The part of the data hierarchy that represents one instance of an entity is a:

A. Field

B. Record

C. File

D. Database

Study Break #1

Chapter 3-15

The part of the data hierarchy that represents one instance of an entity is a:

A. Field

B. Record

C. File

D. Database

Study Break #1 - Answer

Chapter 3-16

Within the context of databases, the term “concurrency” refers to the possibility that:

A. A customer of one store might also be a customer of another store

B. Two database users might want to access the same record at the same time

C. A credit entry for a customer requires a debit entry for a matching account

D. None of these

Study Break #2

Chapter 3-17

Within the context of databases, the term “concurrency” refers to the possibility that:

A. A customer of one store might also be a customer of another store

B. Two database users might want to access the same record at the same time

C. A credit entry for a customer requires a debit entry for a matching account

D. None of these

Study Break #2 - Answer

Chapter 3-18

REA Model

Resources Organization’s assets

Events Activities associated with a business processes

Agents People associated with business activities

Chapter 3-19

Identify Business and Economic Events

Identify Entities

Identify Relationships Among Entities

Steps in DevelopingDatabases with REA

Chapter 3-20

Create Entity-Relationship Diagrams

Identify Attributes of Entities

Convert E-R Diagrams into Database Tables

Steps in DevelopingDatabases with REA

Chapter 3-21

Types of Events Business Economic

Types of Database Entities Entities Agents Resources

Identify Events and Entities

Chapter 3-22

Entity Examples

Chapter 3-23

Identify RelationshipsAmong Entities

Types of Relationships Direct relationship Indirect relationship

Cardinalities Nature of relationships among entities

Chapter 3-24

Cardinality Relationships

Notations One-to-one (1:1) One-to-many (1:N) Many-to-many (N:N)

Purpose Occurrence of one entity Associated with occurrence of one event of another entity

Chapter 3-25

Cardinality Relationships

Chapter 3-26

Purpose Diagram entities Relationships among entities

Structure Rectangles represent entities Connecting lines represent relationships

Entity-Relationship Diagram

Chapter 3-27

E-R Diagram Example

Chapter 3-28

Relationship Tables

Provide greater flexibility

Need for Relationship Tables Linking tables with foreign keys Many-to-many relationships

Chapter 3-29

Relationship Tables

Chapter 3-30

Schematic of Database Tables

Chapter 3-31

In the REA model, the “A” stands for:

A. Agents

B. Additions

C. Accounts

D. Associations

Study Break #3

Chapter 3-32

In the REA model, the “A” stands for:

A. Agents

B. Additions

C. Accounts

D. Associations

Study Break #3 - Answer

Chapter 3-33

Which of these is not a cardinality between two database entities?

A. One-to-one

B. None-to-none

C. One-to-many

D. Many-to-many

Study Break #4

Chapter 3-34

Which of these is not a cardinality between two database entities?

A. One-to-one

B. None-to-none

C. One-to-many

D. Many-to-many

Study Break #4 - Answer

Chapter 3-35

Normalization

Normalization Methodology ensuring attributes are stored in most

appropriate tables Design promotes accuracy Avoids redundancy of data storage

Levels First normal form Second normal form Third normal form

Chapter 3-36

Unnormalized Data

Chapter 3-37

First Normal Form

In First Normal Form (1 NF) when: All data fields are singular Each attribute has one value

Problems Data redundancy Insertion anomaly Deletion anomaly

Chapter 3-38

First Normal Form Example

Chapter 3-39

Second Normal Form

In Second Normal Form (2 NF) when: It is in 1 NF All data items depend on primary record key

Benefits More efficient design Eliminates data redundancy

Chapter 3-40

Second Normal Form Example

Chapter 3-41

Third Normal Form

In Third Normal Form (3 NF) when: It is in 2 NF Does not contain transitive dependencies Data field A does not determine data field B

Ultimate Goal Create database in 3 NF

Chapter 3-42

Third Normal Form Example

Chapter 3-43

A database is in third normal form (3NF) if it is second normal form and:

A. All the data attributes in a record are well defined

B. All the data attributes in a record depend on the record key

C. The data contain to transitive dependencies

D. The data can be stored in two or more separate tables

Study Break #5

Chapter 3-44

A database is in third normal form (3NF) if it is second normal form and:

A. All the data attributes in a record are well defined

B. All the data attributes in a record depend on the record key

C. The data contain to transitive dependencies

D. The data can be stored in two or more separate tables

Study Break #5 - Answer

Chapter 3-45

Copyright

Copyright 2012 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without theexpress written permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchasermay make backup copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages, caused by the use of these programs or from the use of the information contained herein.

Chapter 3-46

Chapter 3