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1 Agenda 01/13/05 Announcement Database Development Process (Chapter 2)
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Transcript of 1 Agenda 01/13/05 Announcement Database Development Process (Chapter 2)
2
Announcement
• A Quiz about Chapter 9 on Tuesday, 01/18/05– Open book– Bring your database textbook (or a copy of chapter 9)
to the class
• For your diagramming software, visit the following web site and download a RFlow trial version:
http://graphicssoft.about.com/cs/diagramswpc
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“It is a capital mistake to theorize before one has data”Sherlock Holms’ remarks in A Scandal in Bohemia (Sir Conan Doyle, 1891)
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8 Underlying Principles of
Systems Development 1. Get the Users Involved2. Use a Problem-Solving Approach
3. Establish Phases and Activities
4. Establish Standards for Consistent Development and Documentation
5. Justify Systems as Capital Investments6. Don’t Be Afraid to Cancel or Revise Scope
7. Divide and Conquer8. Design Systems for Growth and Change
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Strategies for IS Development
Top-Down
Proceeds from general to specific Particular systems are designed working from a
broad knowledge of the entire organizations information needs
Bottom-Up
Proceeds from specific to general Individual systems are designed from a detailed
knowledge of a distinct application
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Information Systems Development Process
Sources Information systems planning (top-
down) User application requests (bottom-up)
IS Development Approaches Systems Development Life Cycle (SDLC) Rapid Application Development (RAD)
- Prototyping
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Information Systems Planning Process
IS Development Projects(i.e. Database Development)IS Development Projects
(i.e. Database Development)
Organization Mission
Organization Mission
Business AssessmentBusiness
Assessment
Organization Strategic PlanOrganization Strategic Plan Current IT ArchitectureCurrent IT Architecture
IS Strategic PlanIS Strategic Plan
New IT ArchitectureNew IT Architecture
IS Operational PlanIS Operational Plan
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Systems Development Life Cycle (SDLC)
1. System Identification and Selection2. Project Initiation and Planning3. Analysis4. Logical Design5. Physical Design6. Implementation7. Maintenance
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System Identification and Selection
• Problem determination• Understanding of the business
situation• Feasibility study• Justification for the system• Authorization to proceed• Priority
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Project Initiation and Planning
• Scope of the project
• Project schedule
• Resource requirements
• Systems architecture
• Enterprise data model
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Project Planning
Analysis
Implementation
Logical Design
Physical Design
MaintenanceDatabase SDLC
RequirementsE-R Data Model
Relational database ModelQulaity Control Checks
Technical SpecificationsDefine the database to the
DBMS
Data EntryInformation Retrieval
(SQL)
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Database Development Activities in
the SDLC
1. Planning
2. Analysis
3. Logical Design
4. Physical Design
5. Implementation
6. Maintenance
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Planning
Examine the information systems architecture (blue print)
Review the enterprise data model
• Establish the general scope of the database
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Analysis
• Determine the specific data requirements for the system
• Create the conceptual data model: Entity-Relationship Diagram (ERD)
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PROFESSOR COURSE
IsQualified
IsScheduled
(4)
Prof-IDProf-Name
Course-NumCourse-Title
Semester
E-R Diagram Example
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Logical Design
• Convert the data model to a database design: Relational Schema
• Perform quality control tuning on the logical database design
- Integrity constraints
- Normalized relations
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E-R Diagram
HAS EXPENSE
Relations (plus Relational SCHEMA)
ACCOUNT (ACCOUNT_NO, ……)EXPENSE (EXPENSE_CODE, ACCOUNT_NO)
Plus Constraints, Integrity Rules, Domain……….
ACCOUNT
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Physical Design
Stipulate technical data specifications
Define the database design to the DBMS
• Construct data entry mechanisms
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Maintenance
Tune the database for performance
Provide security and recovery
• Support the software and files
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Schema
• The conceptual organization of the entire database as viewed by stakeholders
• The structure that contains descriptions of objects created by a user such as tables, views and constraints
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Three Schema Architecture for Database Development
Conceptual Schema Analysis phase: E-R Diagram Logical Design phase: Relational (Logical)
Schema
Internal Schema Physical Design phase: DBMS Definition
External Schema Implementation phase: User Views
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Reports(user View)
Forms(User view)
Programs(User View)
ConceptualSchema
InternalSchema
Three SchemaDatabase
Architecture
External Schema
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Components of Application Logic Involving Data
Input / Output Manage user input from the keyboard Format and present output (screens and
hardcopy)Processing Data validation Business rules Data update Data and information retrievalStorage Performance Security
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People in Database Development Systems analysts
ProgrammersDatabase analystsDatabase and data administratorsSystems programmers &
network administratorsTechnical writersUsers