The%20database%20development%20process

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Chapter 2

• The database development process

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Information Systems Architecture

• A conceptual blueprint or plan that expresses the
  desired future structure for the information
  systems in an organization.

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Architecture example
Data validation and retention
Integrated data warehouse Access analysis and
presentation tools Information delivery system
CIM
Business Operations
EDI
Customers Suppliers
External Events
External database access
Dialogue
Decision makers Customers, Suppliers
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A more sophisticated example...
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Information Systems Architecture

• Key components
• data
• processes which manipulate data
• network which transports data
• people who perform processes and send and receive
  data
• events and points in time when processes are
  performed
• reasons for events and rules which govern data
  processing

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Information Engineering

• An Information Systems Architecture is developed
  by IS planners following a particular methodology
  such as Information Engineering.

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Information Engineering

• Data-oriented methodology
• Uses top-down planning in which specific
  information systems are deduced from a broad
  understanding of organizations information
  needs, rather than relying on specific user
  information requests
• Offers perspective on relationship of information
  systems to business objectives

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Top-Down vs. Bottom-Up

• Top-Down Planning
• A methodology that attempts to gain a broad
  understanding of the information system needs of
  the entire organization

• Bottom-Up Planning
• A methodology that identifies and defines IS
  development projects based upon solving
  operational business problems or taking advantage
  of business opportunities

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The big picture...

• Information engineering
• Information systems planning
• Identify strategic planning factors (goals, CSFs,
  problem areas)
• IT vision
• Identify corporate planning objectives
• Information system architecture
• Develop enterprise model
• Systems analysis
• Systems design
• implementation

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Systems Development Life Cycle
Project Identification Selection
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Database SDLC
Database Development Activities
SDLC
Identify Project
Enterprise Modeling
Initiate and Plan
Conceptual Data Modeling
Analyze
Logical DB Design
Logical Design
Physical DB Design/Creation
Physical Design
DB Implementation
Implementation
DB Maintenance
Maintenance
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Planning Matrixes

• Show interrelationships between objects. Among
  the possibilities
• Location-to-Function
• Unit-to-Function
• Information System-to-Data Entity
• Supporting Function-to-Data Entity
• Information System-to-Objective

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Business Function-to-Data Entity Planning Matrix
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Information System-to-Objective Planning Matrix
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Functional Decomposition
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Enterprise Data Modeling

• The first step in database development, in which
  the scope and general contents of organizational
  databases are specified.

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Enterprise Data Model

• A model which includes
• overall range of organizational databases
• general contents of organizational databases
• Built as part of IS planning for the organization
  and not the design of a particular database
• One part of an organizations overall information
  systems architecture (ISA)

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Conceptual Database Modeling

• Determine user requirements
• Determine business rules
• Build conceptual data model
• outcome is an entity-relationship diagram or
  similar communicationtool
• population of repository

Enterprise Modeling
Conceptual Data Modeling
Logical DB Design
Physical DB Design/Creation
DB Implementation
DB Maintenance
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Logical Database Design

• Select logical database model
• commit to a database alternative
• Map Entity-Relationship Diagrams
• Normalize data structures
• Specify business rules

Enterprise Modeling
Conceptual Data Modeling
Logical DB Design
Physical DB Design/Creation
DB Implementation
DB Maintenance
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Physical Database Design

• Select DBMS
• Select storage devices
• Determine access methods
• Design files and indexes
• Determine database distribution
• Specify update strategies

Enterprise Modeling
Conceptual Data Modeling
Logical DB Design
Physical DB Design/Creation
DB Implementation
DB Maintenance
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Database implementation

• Code and test database processing programs
• Complete documentation
• Install database and convert data

Enterprise Modeling
Conceptual Data Modeling
Logical DB Design
Physical DB Design/Creation
DB Implementation
DB Maintenance
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Database Maintenance

• Analyze database and applications to ensure
  evolving information requirements are being met
• Tune database for improved performance
• Fix errors
• Provide data recovery when needed

Enterprise Modeling
Conceptual Data Modeling
Logical DB Design
Physical DB Design/Creation
DB Implementation
DB Maintenance
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Documentation

• most formal development methodologies are
  documentation based
• helps managers monitor progress and quality of
  project
• facilitates communication between team members
• includes models
• various stages are not complete until
  documentation is accepted

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Some Keys to Success...

• accurate requirements definition
• commitment
• effective change management
• manageable size
• champion

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So
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Three Schema Architecture for Database Development

• Conceptual Schema
• Analysis project phase
• External Schema
• Analysis and Logical Design phases
• (subset of conceptual schema)
• Internal Schema
• Physical Design phase

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3-schema architecture
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Conceptual Schema

• Describes the logical structure of the entire
  database
• Independent of a specific DBMS
• Avoids details of physical design
• Stated in
• ERDs
• metadata

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External Schema

• Also called a user view
• Specifications include screen formats, report
  formats, transaction definitions

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Physical Schema

• Describes physical structure of entire database
• Specifies how data from a conceptual schema are
  stored in secondary memory
• Sometimes called internal schema
• Specifications include physical file and data
  structures, storage organization, and index
  structures

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3-schema development process
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Rapid application development

• design methodology which speeds systems delivery
  through a combination of speedy design
  iterations, data modeling, user/developer
  teamwork, and automated development tools.
• encompasses a set of techniques that can be used
  to build complex, strategic, and mission-critical
  applications in months rather than years

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RAD
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The RAD lifecycle

• requirements planning
• conduct joint requirement planning workshop
• design
• conduct JAD workshop
• construction
• members of team monitor evolution, system is
  prototyped
• cutover
• installation

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Within the time box...
Requirements planning
User design
construction phase
build and evolve prototype
User review
time box
request for change
Evaluate system
cutover
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Barriers to overcome...

• poor training/ tools
• reluctance to leave old methods behind
• mindset that RAD is not adequate for large-scale
  systems development
• speedy delivery does not mean low quality
• creeping functionality