chapter 3-1 chapter 3: data modeling introduction an overview of databases steps in developing a...
TRANSCRIPT
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