1. Database Design Using the REA Data Model
Chapter 17 = chapter 15 in 10e
Database Design Using the REA Data Model
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2. Learning Objectives
Discuss the steps for designing and implementing a database system.
Use the REA data model to design an AIS database.
Draw an REA diagram of an AIS database.
Read an REA diagram and explain what it reveals about the business activities and policies of the organization being modeled.
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3. Database Design Process
System Analysis
Conceptual Design
Physical Design
Implementation & Conversion
Operation & Maintenance
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4. The System Analysis Process
Systems Analysis
Initial planning to determine the need for and feasibility of developing a new system
Judgments about the proposal’s technological and economic feasibility
Identify user information needs
Define the scope of the proposed new system
Gather information about the expected number of users and transaction volumes to make preliminary decisions about hardware and software requirements
Conceptual Design
Developing the different schemas for the new system at the conceptual, external, and internal levels
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5. The System Analysis Process (cont’d)
Physical Design
Translating the internal-level schema into the actual database structures that will be implemented in the new system
New applications are developed
Implementation and Conversion
Includes all the activities associated with transferring data from existing systems to the new database AIS
Testing the new system
Training employees
Maintaining the New System
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6. Data Modeling
Process of defining an information system so it represents an organizations requirements
Occurs at two stages of the design process:
System analysis
Conceptual design
Data models:
Data flow diagrams (Chapter 3)
Flow charts (Chapter 3)
Entity-relationship diagrams (Chapter 17)
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7. Entity-Relationship Diagrams
Used to graphically represent a database schema
Depicts entities
Anything an organization wants to collect information about
Relationships between entities
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8. E-R Diagram Variations
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9. Resources-Events-Agents Diagram
Developed for designing AIS
Categorizing entities into:
Resources
Things that have economic value
Events
Business activities
Management wants to manage and control
Agents
People and organizations that participate in events
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10. REA Diagram Rules
Each event is linked to at least one resource that it affects.
Each event is linked to at least one other event.
Types of links (relationships):
Get events
Give events
Participation events
Each event is linked to at least two participating agents.
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11. Business Cycle Give–Get Relationships
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12. Revenue Cycle REA Diagram
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13. Developing an REA Diagram
Identify the events about which management wants to collect information.
Identify the resources affected by each event and the agents who participate in those events.
What economic resource is reduced by the “Give” event?
What economic resource is acquired by the “Get” event?
What economic resource is affected by a commitment event?
Determine the cardinalities of each relationship.
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14. Cardinalities Describe the nature of relationships between entities
How many instances of one entity can be linked to each specific instance of another entity
Minimum can be: 0 or 1
Maximum can be: 1 or Many
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15. Three Types of Relationships
Relationship type is based on maximum cardinality:
One-to-One:
One-to-Many:
Many-to-Many:
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