database & information system
TRANSCRIPT
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Compiled by:
Ayaz Sandeelo
INFORMATION SYSTEM &SYSTEM DEVELOPMENT
LIFE CYCLE (SDLC)
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DefinitionsData
Raw facts such as an employees name and number
of hours worked in a week, inventory part numbersor sales orders.
Information
A collection of facts organized in such a way thatthey have additional value beyond the value of thefacts themselves.
DataInformation
$35,000 12 Units$12,000 J. JonesWestern Region$100,000 100
Units 35 Units
DataProcessing
Salesperson: J.Jones SalesTerritory: WesternRegion Current
Sales: 147 Units =147 000
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Information Systems
An information system(IS) is typically considered to be a set of
interrelated elements or components that collect(input),
manipulate(processes), and disseminate (output) data and
information and provide a feedback mechanism to meet an
objective.
Open System
Close System
Definitions
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An Information System is an organized combination of people,
hardware, software, communication networks and the dataresources that collects, transforms and disseminates informationin a organization.
Computer-based Information System
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Classification of IS
Information
Systems
OperationsSupport System Management
Support System
Transactionprocessingsystems
Processcontrolsystems
Officeautomationsystems
Managementinformationsystems
Decisionsupportsystems
Executiveinformationsystems
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1. Operations support systems process data generatedby business operations
Major categories are:i) Transaction processing systems
ii) Process control systems
iii) Office automation systems2. Management Support Systems provide information
and support needed for effective decision making bymanagers
Major categories are
i) Management Information System
ii) Decision Support Systems
iii) Executive Information System
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1. Operations Support System
i) Transaction processing systems
Process business exchanges
Maintain records about the exchanges
Handle routine, yet critical, tasks
Perform simple calculations
ii) Process control systems monitor and control industrialprocesses.
iii) Office automation systems automate officeprocedures and enhance office communications andproductivity.
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2. Management support systems provide informationand support needed for effective decision making bymanagers
Major categories are:
i) Management information systems
Routine information for routine decisions
Operational efficiency
Use transaction data as main input Databases integrate MIS in different functional areas
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ii) Decision Support SystemInteractive support for non-routine decisions or problems End-users are more involved in creating a DSS than anMIS
iii) Executive information systems
provide critical information tailored to the information needsof executives
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Other categories
a) Expert systems
b) End user computing systemsc) Business information systems
d) Strategic information systems
a) Expert Systems are knowledge-based systems thatprovides expert advice and act as expert consultants tothe users
b) End user computing systems support the direct, hands
on use of computers by end users for operational andmanagerial applications
c) Business information systems support the operational andmanagerial applications of the basic business functions of
a firm
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Six Phases of the System
Development Life Cycle
Preliminary InvestigationAssesses feasibility and practicality of system
System Analysis Study old system and identify new requirements
Defines system from user's view
System Design
Design new/alternative system Defines system from technical view
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Six Phases of the System
Development Life Cycle
System Development
New hardware and software is acquired, developed,
and tested System Implementation
System installation and training
System Operation & Maintenance Daily operation
Periodic evaluation and updating
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SDLC PhasesPreliminaryInvestigation
System Operation& Maintenance
SystemAnalysis
SystemImplementationn
SystemDesign
SystemDevelopment
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Phase 1:
Preliminary Investigation
Determine if a new system is needed
Three primary tasks:
Define the problem
By observation and interview, determine what information is
needed by whom, when, where and why
Suggest alternative solutions
Prepare a short report
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Phase 2:
System Analysis
In depth study of the existing system to
determine what the new system should do.
Expand on data gathered in Phase 1
In addition to observation and interviews,
examine:
Formal lines of authority (org chart) Standard operating procedures
How information flows
Reasons for any inefficiencies
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Phase 2: System Analysis
Tools Used
Checklists - list of questions
Top-down analysis - start with top levelcomponents, break down into smaller partsthrough each successive level
Grid charts - to show relationship between
inputs and outputs System flowcharts - charts flow of input data,
processing, and output which show systemelements and interactions
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Phase 2: System Analysis
Documentation Produced
Complete description of current system and its
problems
Requirements for for new system including:
Subject
Scope
Objectives
Benefits
Possible development schedule
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Phase 3:
System Design Uses specifications from the systems analysis
to design alternative systems
Evaluate alternatives based upon:
Economic feasibility - Do benefits justify costs?
Technical feasibility - Is reliable technology and
training available?
Operational feasibility - Will the managers and
users support it?
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Phase 3: System Design
Tools Used Computer-Aided Software Engineering (CASE)
tools are software-based products designed tohelp automate the production of informationsystems.
Examples:
Diagramming Tools
Data Repositories Prototyping Tools
Test Data Generators
Documentation Tools
Project Management Tools
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Phase 3: System Design
Documentation Produced
System Design Report
Describe Alternatives including:
Inputs/Outputs
Processing
Storage and Backup
Recommend Top Alternative based upon: System Fit into the Organization
Flexibility for the future
Costs vs. benefits
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Phase 4:
System Development
Build the system to the design specifications Develop the software
Purchase off-the-shelf software OR Write custom software
Acquire the hardware
Test the new system
Module (unit) test - tests each part of system Integration testing - tests system as one unit
Create manuals for users and operators
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Phase 5:
System Implementation
Convert from old system to new system
Train users Compile final documentation
Evaluate the new system
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Phase 5: System Implementation
Types of Conversion Direct/plunge/crash approach entire new system
completely replaces entire old system, in one step
Parallel approach - both systems are operated side
by side until the new system proves itself
Pilot approach - launched new system for only onegroup within the business -- once new system is
operating smoothly, implementation goes company-
wide
Phased/incremental approach - individual parts ofnew system are gradually phased-in over time, using
either crash or parallel for each piece.
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Phase 5: System Implementation
User Training
Ease into system, make them comfortable, and gain
their support Most commonly overlooked
Can be commenced before equipment delivery
Outside trainers sometimes used
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Phase 6: Operations & Maintenance
Types of changes:
Physical repair of the system
Correction of new bugs found (corrective) System adjustments to environmental changes
Adjustments for users changing needs (adaptive)
Changes to user better techniques when they become
available (perfective)
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Phase 6: Operations & Maintenance
Evaluation Methods
Systems audit - performance compared to original
specifications
Periodic evaluation - checkups from time to time,
modifications if necessary
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Deliverables of the SDLC
Begin buildingnew system
System convertedUsers trained
Coded andTested System
Design Specifications
PreliminaryInvestigation
SystemAnalysis
SystemDesign
SystemImplementation
SystemDevelopment
SystemMaintenance
Approved FeasibilityStudy
Operational System
Documentation completed
Abort Project
Goto next phase
Goto Previous phaseProblemSpecifications
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Tools Of Analysis
HIPO Technique
DFD and ERD
System Flow Chart
Case Tools
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HIPO HIPO diagram) HIPO for hierarchical input
process output is a "popular 1970s systems
analysis design aid and documentation.
HIPO are used most commonly to diagram either
data structures or code structures
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DFD & ERD
DFD STANDS FOR Data Flow diagram is a symbolicstructure which shows the flow of data how it is
used in different stages in a particular process.
actually dfd is used to define how data flow from one
process to another process
ERD STANDS FOR (Entity Relationship Diagram).ER diagram is Entity Relationship Diagram which
shows relationship between different entities in aprocess. ERD diagram is used to define relation
between different entities.
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COMPUTER-AIDED SOFTWAREENGINEERING (CASE)
Computer-aided software engineering (CASE) isthe use of software tools to assist in the
development and maintenance of software. Tools
used to assist in this way are known as CASE
Tools.Some typical CASE tools are:
Code generation tools
Data modeling tools
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Flow Chart
A flow chart is a graphical or symbolic representation
of a process. Each step in the process is represented
by a different symbol and contains a short description
of the process step. The flow chart symbols are linked
together with arrows showing the process flow
direction.
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Common Flowchart Symbols
Different flow chart symbols have different meanings. Themost common flow chart symbols are:
Terminator: An oval flow chart shape indicating the start orend of the process.
Process: A rectangular flow chart shape indicating anormal process flow step.
Decision: A diamond flow chart shape indication a branchin the process flow.
Connector: A small, labeled, circular flow chart shapeused to indicate a jump in the process flow. (Shown as thecircle with the letter A, below.)
Data: A parallelogram that indicates data input or output(I/O) for a process.
Document: Used to indicate a document or report (seeimage in sample flow chart below).
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