Transcript Document

Chapter 2
Database Development Process
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Objectives
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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
Draw simple data models
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Enterprise Data Model
• First step in database development
• Specifies scope and general content
• Overall picture of organizational data at high
level of abstraction
• Entity-relationship diagram
• Descriptions of entity types
• Relationships between entities
• Business rules
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Segment from enterprise data a
simplified E-R diagram
Enterprise data model
describes the high-level
entities in an organization
and the relationship between
these entities
Pine Valley Furniture Company
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Another Simpler View
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Information Systems Architecture
(ISA)
• Conceptual blueprint for organization’s
desired information systems structure
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Information Systems Architecture
(ISA) Consists of
• People
• Data
– (e.g. Enterprise Data
Model – simplified
ER Diagram)
• Processes
– data flow diagrams,
process
decomposition, etc.
• Data Network
– people management
using project
management tools (Gantt
charts, etc.)
• Events and points in
time
– when processes are
performed
• Reasons for events and
rules
– (e.g. decision tables)
– topology diagram
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Information Engineering
• A data-oriented methodology to create
and maintain information systems
• Top-down planning:
– a generic IS planning methodology
– for obtaining a broad understanding of the
IS needed by the entire organization
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Information Engineering
• Four steps to Top-Down planning:
– Planning
– Analysis
– Design
– Implementation
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Information Systems Planning
• Purpose
– align information technology with
organization’s business strategies
• Three steps:
• Identify strategic planning factors
• Identify corporate planning objects
• Develop enterprise model
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Identify Strategic Planning Factors
• Organization goals
– what we hope to accomplish
• Critical success factors
– what MUST work in order for us to survive
• Problem areas
– weaknesses we now have
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Identify Corporate Planning
Objects
• Organizational units
– departments
• Organizational locations
• Business functions
– groups of business processes
• Entity types
– the things we are trying to model for the database
• Information systems
– application programs
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Develop Enterprise Model
• Functional decomposition
– See Figure 2-2
– Top down design
– Looks like structure chart
• Enterprise data model
– See Figure 2-1
– Entity relationships
• Planning matrixes
– See Figure 2-3
– Looks like a decision table
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Example of process decomposition
of an order fulfillment function
Decomposition -- breaking
large tasks into smaller tasks
in a hierarchical structure
chart
Pine Valley Furniture
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Planning Matrixes
• Describe relationships between
planning objects in the organization
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Planning Matrixes Types
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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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Business
Function (users)
Business Planning
Product Development
Materials Management
Order Fulfillment
Order Shipment
Sales Summarization
Production Operations
Finance and Accounting
Customer
Product
Raw Material
Order
Work Center
Work Order
Invoice
Equipment
Employee
Data Entity
Types
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X X X
X X X
Example business function-to-data entity matrix
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Two Approaches to Database and
IS Development
• System Development
Life Cycle (SDLC)
– Detailed, well-planned
development process
– Time-consuming, but
comprehensive
– Long development cycle
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• Prototyping
– 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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Systems Development Life Cycle
SDLC
Project Identification
and Selection
Project Initiation
and Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance
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SDLC (cont.)
Project Identification
Project
Identification
and
and Selection
Selection
Database activity –
enterprise modeling
Project Initiation
and Planning
Analysis
Logical Design
Physical Design
Implementation
Purpose --preliminary understanding
Deliverable –request for project
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Database activity –
conceptual data modeling
Project
Project Initiation
Initiation
and
and Planning
Planning
Analysis
Logical Design
Physical Design
Implementation
Purpose – state business situation and solution
Deliverable – request for analysis
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Database activity –
conceptual data modeling
Project Initiation
and Planning
Analysis
Analysis
Logical Design
Physical Design
Implementation
Purpose – thorough analysis
Deliverable – functional system specifications
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Database activity –
logical database design
Project Initiation
and Planning
Analysis
Logical
Logical Design
Design
Physical Design
Implementation
Purpose – information
requirements structure
Deliverable – detailed design specifications
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Project Initiation
and Planning
Database activity –
physical database design
Analysis
Logical Design
Physical
Physical Design
Design
Implementation
Purpose – develop technology specs
Deliverable – program/data
structures, technology purchases,
organization redesigns
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Database activity –
database implementation
Project Initiation
and Planning
Analysis
Logical Design
Physical Design
Implementation
Implementation
Purpose – programming, testing, training,
installation, documenting
Deliverable – operational programs,
documentation, training materials
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Maintenance
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SDLC (cont.)
Project Identification
and Selection
Project Initiation
and Planning
Database activity –
database maintenance
Analysis
Logical Design
Physical Design
Implementation
Purpose – monitor, repair, enhance
Deliverable – periodic audits
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Maintenance
Maintenance
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Prototyping Methodology and
Database Development Process
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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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CASE
• Computer-Aided Software Engineering
(CASE)
– software tools providing automated support
for systems development
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CASE Database Features
• Data modeling
– entity-relationship diagrams
• Code generation
– SQL code for table creation
• Repositories
– knowledge base of enterprise information
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Managing Projects
• Project
– a planned undertaking of related activities
to reach an objective that has a beginning
and an end
• Involves use of review points for:
– Validation of satisfactory progress
– Step back from detail to overall view
– Renew commitment of stakeholders
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Managing Projects
• Incremental commitment
– review of systems development project
after each development phase with
rejustification after each phase
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Managing Projects:
People Involved
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Systems analysts
Database analysts
Users
Programmers
Database/data administrators
Systems programmers, network
administrators, testers, technical writers
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Gantt Chart
Shows time estimates of tasks
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PERT Chart
Shows dependencies between tasks
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Database Schema
• External Schema
• Physical Schema
– Physical structures –
covered in chapters
5 and 6
• Conceptual Schema
– E-R models –
covered in chapters
3 and 4
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– User Views
– Subsets of
Conceptual Schema
– Can be determined
from businessfunction/data entity
matrices
– DBA determines
schema for different
users
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Different people
have different
views of the
database…these
are the external
schema
The internal
schema is the
underlying
design and
implementation
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Developing the 3-tiered Architecture
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Three-tiered Client/Server Database
Architecture
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Pine Valley Furniture
Segment of project data model
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Database Definition
For Home Office product line
marketing support system
Access Data Model Prototype
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Four Relations (PVF)
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Four Relations
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Homework Assignment
• Homework Assignment 2
• Read Chapter 3
• In-Class Project in Teams
– Pages 33-35, 76-82
– Answer the following:
• Question 6, Pg. 34
• Project Exercises 1, 2, 4, 5a,5b & 6, Pgs. 34-35
• Be prepared to discuss and provide alternatives to
Questions 3, 4, 5, & 6, Pg. 79
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