Database & Information System

7/31/2019 Database & Information System

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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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Database & Information System