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

2. Introduction Uses of a modern AIS Systematically record data
Provide convenient and useful formats
Easy access to information

3. What is a Database? Collection of organized data
Used by many different computer applications
Manipulated by database management systems (DBMS)

4. Significance of a Database
Critical information
Volume
Distribution
Privacy
Irreplaceable data
Need for accuracy
Internet uses

5. Storing Data in Databases
Data must be stored and organized systematically
Three important concepts:
Data hierarchy
Record structures
Database keys

6. Data Hierarchy Data organization in ascending order: Data field Record
File
Database

7. Record Structures Data fields in each record of a database table
Structure is usually fixed
Example

8. Database Keys Primary Key Foreign Keys Unique to each record
Enable referencing of one or more records
Matches primary key of related table

9. Records Combined Into Report

10. Additional Database Issues
Administration
Database Administrator
Documentation
Includes a variety of descriptions
Structures, Contents, Security Features
Data Dictionary
Metadata

11. Data Dictionary Example

12. Additional Database Issues
Data Integrity
Data Integrity controls
Designed by database developers
Processing Accuracy and Completeness
Transaction controls
Ensures accurate transaction processing

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

14. Study Break #1
The part of the data hierarchy that represents one instance of an entity is a:
Field
Record
File
Database

15. Study Break #1 - Answer
The part of the data hierarchy that represents one instance of an entity is a:
Field
Record
File
Database

16. Study Break #2
Within the context of databases, the term “concurrency” refers to the possibility that:
A customer of one store might also be a customer of another store
Two database users might want to access the same record at the same time
A credit entry for a customer requires a debit entry for a matching account
None of these

17. Study Break #2 - Answer
Within the context of databases, the term “concurrency” refers to the possibility that:
A customer of one store might also be a customer of another store
Two database users might want to access the same record at the same time
A credit entry for a customer requires a debit entry for a matching account
None of these

18. REA Model Resources Events Agents Organization’s assets
Activities associated with a business processes
Agents
People associated with business activities

19. Steps in Developing Databases with REA
Identify Business and Economic Events
Identify Entities
Identify Relationships Among Entities

20. Steps in Developing Databases with REA
Create Entity-Relationship Diagrams
Identify Attributes of Entities
Convert E-R Diagrams into Database Tables

21. Identify Events and Entities
Types of Events
Business
Economic
Types of Database Entities
Entities
Agents
Resources

22. Entity Examples

23. Identify Relationships Among Entities
Types of Relationships
Direct relationship
Indirect relationship
Cardinalities
Nature of relationships among entities

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

25. Cardinality Relationships

26. Entity-Relationship Diagram
Purpose
Diagram entities
Relationships among entities
Structure
Rectangles represent entities
Connecting lines represent relationships

27. E-R Diagram Example

28. Relationship Tables Provide greater flexibility
Need for Relationship Tables
Linking tables with foreign keys
Many-to-many relationships

29. Relationship Tables

30. Schematic of Database Tables

31. Study Break #3 In the REA model, the “A” stands for: Agents Additions
Accounts
Associations

32. Study Break #3 - Answer In the REA model, the “A” stands for: Agents
Additions
Accounts
Associations

33. Study Break #4
Which of these is not a cardinality between two database entities?
One-to-one
None-to-none
One-to-many
Many-to-many

34. Study Break #4 - Answer
Which of these is not a cardinality between two database entities?
One-to-one
None-to-none
One-to-many
Many-to-many

35. Normalization Normalization Levels
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

36. Unnormalized Data

37. First Normal Form In First Normal Form (1 NF) when: Problems
All data fields are singular
Each attribute has one value
Problems
Data redundancy
Insertion anomaly
Deletion anomaly

38. First Normal Form Example

39. Second Normal Form In Second Normal Form (2 NF) when: Benefits
It is in 1 NF
All data items depend on primary record key
Benefits
More efficient design
Eliminates data redundancy

40. Second Normal Form Example

41. Third Normal Form In Third Normal Form (3 NF) when: Ultimate Goal
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

42. Third Normal Form Example

43. Study Break #5
A database is in third normal form (3NF) if it is second normal form and:
All the data attributes in a record are well defined
All the data attributes in a record depend on the record key
The data contain to transitive dependencies
The data can be stored in two or more separate tables

44. Study Break #5 - Answer
A database is in third normal form (3NF) if it is second normal form and:
All the data attributes in a record are well defined
All the data attributes in a record depend on the record key
The data contain to transitive dependencies
The data can be stored in two or more separate tables

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46. Chapter 3