1 Agenda 01/13/05 Announcement Database Development Process (Chapter 2)

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Agenda01/13/05

• Announcement

• Database Development Process (Chapter 2)

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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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Database Development Process

(Chapter 2)

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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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Analysis

       System requirements (detailed)

       Conceptual model

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Logical Design

    Functional specification of system components

(detailed)

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Physical Design

       Technical specification of system components (detailed)

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Implementation

       System installation

•       Applications

•       Documentation

•       Training

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Maintenance

• System Monitoring

• Repairing

• Upgrade

• Support

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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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ACCOUNT EXPENSEHas

Basic Entity-Relationship Example

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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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Implementation

    Load the data

    Build the applications

• Produce documentation

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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

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To Download RFFLOW Software

Go to

http://graphicssoft.about.com/cs/diagramswpc