Chapter 2: The Database Development Process

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Chapter 2 The Database Development Process
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Objectives

• Definition of terms
• Describe system development life cycle
• Explain prototyping approach
• Explain roles of individuals
• Explain three-schema approach
• Explain role of packaged data models
• Explain three-tiered architectures
• Explain scope of database design projects
• Draw simple data models

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Enterprise Data Modeling

• First step in database development
• Specifies scope and general content of
  organizational database
• Overall picture of organizational data at high
  level of abstraction
• Entity-relationship diagram
• Descriptions of entity types
• Relationships between entities

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Figure 2-1 Segment from enterprise data model
Enterprise data model describes the high-level
entities in an organization and the relationship
between these entities
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Information Systems Architecture(ISA)

• Conceptual blueprint for organizations desired
  information systems structure
• Consists of
• Data (e.g. Enterprise Data Modelsimplified ER
  Diagram)
• Processesmanipulate data ( data flow diagrams)
• Data Network- transport data (topology diagram)
• Peoplepeople management using project management
  tools (Gantt charts, etc.)
• Events and points in time-when processes are
  performed (state transition diagram)
• Reasons for events and rules (e.g., decision
  tables)

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Information Engineering

• A data-oriented methodology to create and
  maintain information systems
• Top-down IS planning methodology
• IS are deduced from a broad understanding of the
  Information need of the entire organization
• Not from consolidating many specific information
  requests
• Four steps to Top-Down planning
• Planning
• Analysis
• Design
• Implementation

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Information Systems Planning

• Purposealign information technology with
  organizations business strategies
• Three steps
• Identify strategic planning factors
• Identify corporate planning objects
• Develop enterprise model

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Identify Strategic Planning Factors

• Organization goalswhat we hope to accomplish
• Critical success factorswhat MUST work in order
  for us to survive
• Problem areasweaknesses we now have

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Identify Strategic Planning Factors
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Identify Corporate Planning Objects (Table 2-3)

• Organizational unitsdepartments
• Organizational locations
• Business functionsgroups of business processes
• Entity typesthe things we are trying to model
  for the database
• Information systemsapplication programs

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Develop Enterprise Model

• Functional decomposition
• Iterative process breaking system description
  into finer and finer detail
• Enterprise data model
• Planning matrixes
• Describe interrelationships
• between planning objects

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Figure 2-2 Example of process decomposition of an
order fulfillment function (Pine Valley Furniture)
Decomposition breaking large tasks into smaller
tasks in a hierarchical structure chart
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Planning Matrixes

• Describe relationships between planning objects
  in the organization
• Types of matrixes
• Function-to-data entity
• Location-to-function
• Unit-to-function
• IS-to-data entity
• Supporting function-to-data entity
• IS-to-business objective

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Example business function-to-data entity matrix
(Fig. 2-3)
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Two Approaches to Database and IS Development

• SDLC
• System Development Life Cycle
• Complete set of steps to specify, develop,
  maintain and replace information systems
• Time-consuming, but comprehensive
• Long development cycle
• Prototyping
• Iterative process of system development in which
  requirements are converted to a working system
  that is continuously revised
• Rapid application development (RAD)
• Cursory attempt at conceptual data modeling
• Define database during development of initial
  prototype
• Repeat implementation and maintenance activities
  with new prototype versions

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SDLC
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Systems Development Life Cycle(see also Figures
2.4, 2.5)
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposepreliminary understanding Deliverablerequ
est for study
Planning
Database activity enterprise modeling and early
conceptual data modeling
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposethorough requirements analysis and
structuring Deliverablefunctional system
specifications
Analysis
Database activityThorough and integrated
conceptual data modeling
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposeinformation requirements elicitation and
structure Deliverabledetailed design
specifications
Logical Design
Database activity logical database design
(transactions, forms, displays, views, data
integrity and security)
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposedevelop technology and organizational
specifications Deliverableprogram/data
structures, technology purchases, organization
redesigns
Physical Design
Database activity physical database design
(define database to DBMS, physical data
organization, database processing programs)
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposeprogramming, testing, training,
installation, documenting Deliverableoperational
programs, documentation, training materials
Database activity database implementation,
including coded programs, documentation,
installation and conversion
Implementation
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Systems Development Life Cycle(see also Figures
2.4, 2.5) (cont.)
Purposemonitor, repair, enhance Deliverableperio
dic audits
Database activity database maintenance,
performance analysis and tuning, error corrections
Maintenance
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Prototyping Database Methodology(Figure 2.6)
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Prototyping Database Methodology(Figure 2.6)
(cont.)
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Prototyping Database Methodology(Figure 2.6)
(cont.)
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Prototyping Database Methodology(Figure 2.6)
(cont.)
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Prototyping Database Methodology(Figure 2.6)
(cont.)
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CASE

• Computer-Aided Software Engineering
  (CASE)software tools providing automated support
  for systems development
• Three database features
• Data modelingdrawing entity-relationship
  diagrams
• Code generationSQL code for table creation
• Repositoriesknowledge base of enterprise
  information

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Packaged Data Models

• Model components that can be purchased,
  customized, and assembled into full-scale data
  models
• Advantages
• Reduced development time
• Higher model quality and reliability
• Two types
• Universal data models
• Industry-specific data models

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Managing Projects

• Projecta planned undertaking of related
  activities to reach an objective that has a
  beginning and an end
• Project leader responsible for project planning,
  staffing and supervising project team
• Use of review points for
• Validation of satisfactory progress
• Step back from detail to overall view
• Renew commitment of stakeholders
• Incremental commitmentreview of systems
  development project after each development phase
  with rejustification after each phase

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Managing Projects People Involved

• Business analysts
• Systems analysts
• Database analysts and data modelers
• Users
• Programmers
• Database architects
• Data administrators
• Project managers
• Other technical experts

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Database Schema

• Defined in ANSI/SPARC 1978
• External Schema
• Reflect the view of data users
• Can be determined from business-function/data
  entity matrices
• DBA determines schema for different users
• Conceptual Schema
• Reflect the view of data architect or data
  administrator
• E-R modelscovered in Chapters 3 and 4
• Internal schema covered in chapter 5 and 6
• Logical schema representation of data for a
  type of data management technology
• Physical schema how data from logical schema are
  stored in computers secondary memory

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Figure 2-7 Three-schema architecture
Different people have different views of the
databasethese are the external schema
The internal schema is the underlying design and
implementation
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Figure 2-8 Developing the three-schema
architecture
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Client/server architecture

• A LAN-based environment in which database
  software on a server performs database commands
  sent to it fro client workstations, and
  application programs on each client concentrate
  on user interface functions.

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Figure 2-9 Three-tiered client/server database
architecture
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Readings

• Developing a database application for pine valley
  furniture company
• pp. 57-70, Hoffer 8th ed.