Computers Are Your Future Tenth Edition Chapter 13: Systems Analysis & Design Copyright © 2009...
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Transcript of Computers Are Your Future Tenth Edition Chapter 13: Systems Analysis & Design Copyright © 2009...
Computers Are Your FutureTenth Edition
Chapter 13: Systems Analysis & Design
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 1
2
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America.
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall
What You Will Learn
Explain what systems analysts do. Understand the concept of a
system and its life cycle. Discuss why the systems
development life cycle (SDLC) is so widely used.
List the five phases of the SDLC.
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 3
What You Will Learn
Describe the classic mistakes of failed information systems development projects and how systems analysts can avoid them.
Discuss the activities in each of the five phases of the SDLC.
Name the deliverables of each of the five phases of the SDLC.
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 4
Systems Analysis & Design
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 5
System Analysts: Communication Counts
Systems analysis Involves information systems planning,
development, and maintenance Performed in an organized manner
System analysts determine the information system requirements of an organization based on input from users and management.
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System Analysts: Communication Counts
Systems analysts must possess excellent communication and listening skills to help develop an effective information system.
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The Systems Development Life Cycle
Development of information systems Used to be chaotic Often resulted in inadequate results
Systems development life cycle (SDLC) Means to organize development Consists of five phasesCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 8
The Systems Development Life Cycle
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The Systems Development Life Cycle
Systems Made up of a grouping of parts that
work together to achieve an objective Have life cycles that start with their
creation, go through growth and changes, and end with obsolescence.
Artificial system: Developed by people rather than by nature
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10
The Systems Development Life Cycle
The system development life cycle’s philosophy: You cannot proceed to the
next phase before the previous one is completed.
Each phase must provide a deliverable that often serves as the input for the next phase.
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The Systems Development Life Cycle
Systems development wisdom: Involve users. Use a problem-solving methodology
to provide effective results. Use strong project management
skills.
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The Systems Development Life Cycle
Systems development wisdom (continued): Document all important facts about a
project. Use checkpoints to keep work on
target. Anticipate future growth and change
while designing the system.
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 13
The Systems Development Life Cycle An accepted
concept in the systems development life cycle is the waterfall model, which enables analysts to revisit a prior phase through corrective pathways when problems arise.
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Phase 1: Planning the System
Phase 1 includes the following tasks: Recognizing the needs of the system Defining the problem Examining alternative solutions Developing a plan Determining feasibility Preparing the project proposal
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Phase 1: Planning the System
Recognition of the need for a new or modified system may come from acknowledging deficiencies.
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Phase 1: Planning the System
Defining the problem cannot occur until it is understood Problem: the underlying cause of a
symptom Symptom: the unacceptable result of
a problem Once the problem is defined:
Use requirements analysis to identify the system requirements based on user needsCopyright © 2009 Pearson Education, Inc. Publishing as Prentice
Hall 17
Phase 1: Planning the System
After system requirements are defined: Evaluate potential solutions Create a project plan
Cites the goals of the system Lists the steps or activities to successful
completion of the project Specifies order of completion Estimates time frames
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Phase 1: Planning the System
Gantt chart Type of bar chart Used to provide a graphical summary
of the milestone tasks and their due dates.
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Phase 1: Planning the System
Feasibility studies Technical feasibility: Can be
completed with existing technology Operational feasibility: Can be
accomplished with the available resources
Economic feasibility: Can be done with the available fiscal
resources Often involves a cost-benefit analysis Seeks a return on investment (ROI)
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 20
Phase 1: Planning the System
Project proposal Phase 1 deliverable A written report
Documents details of the system problem and its resolution
Concludes with a recommendation. End of Phase 1 Basis for management decision to
proceed Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 21
Phase 2: Analyzing & Documenting the Existing System
Determine what the new system will do
Two parts: Analyzing the current system Determining the requirements of the
new system Deliverable: List of requirements
for the new systemCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 22
Phase 3: Designing the System
Determine how the new system information will work List and document specifications
using Graphic tools Project dictionaries Data dictionaries
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Phase 3: Designing the System
Design tools used during this phase: Entity-relationship diagram (ERD) Data flow diagram (DFD) Rapid application development (RAD) Computer-aided software engineering
(CASE)
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Phase 3: Designing the System
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Entity relationship diagram
Phase 3: Designing the System
Rapid Application Development (RAD) Also known as prototyping Create small mock-up of system early in
the process Provide enough functionality to get
feedback from users Advantage: Users have something
concrete to reviewCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 26
Phase 3: Designing the System
Computer-Aided Software Engineering (CASE) For complex systems Automates documenting entity
relationships and data flow CASE tools include project management
features, data dictionaries, documentation support, and graphical output support, and some generate prototype code Copyright © 2009 Pearson Education, Inc. Publishing as Prentice
Hall 27
Phase 3: Designing the System
Teams create support material: Project dictionary: defines
terminology Data dictionary: identifies the data
that will be entered into the system
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Phase 3: Designing the System
Phase 3 deliverable: A logical diagram or design that shows how the new system will operate
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Phase 4: Implementing the System
Decide whether to create system or outsource development
Additional tasks: Developing the software Application and acceptance testing User training System conversion
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Phase 4: Implementing the System
Application testing involves assessing the programs separately and as a group.
Acceptance testing is performed by the users and ensures that the system works properly.
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Phase 4: Implementing the System
System conversion methods: Parallel conversion Pilot conversion Phased conversion Direct conversion (crash conversion)
The deliverable in Phase 4 is the completed, tested system.
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Phase 5: Maintaining the System
Review and maintain new system Must meet the needs of the users Must function properly
Perform postimplementation system review Evaluates whether the goals of the
system are met Serves as Phase 5 deliverable
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 33
Computers Are Your FutureTenth Edition
Chapter 12: Databases & Information Systems
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Databases & Information Systems
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The Levels of Data in a Database
A database is a group of data that can be entered, selected, sorted, grouped, reviewed, and produced as output.
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The Levels of Data in a Database
Database units Bit
The smallest unit of data stored by a computer
Contains either a 1 or a 0 Character
A letter, number, or symbol Made of bytes, which are groups of 8 bits
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 37
The Levels of Data in a Database
Database terms Field
Composed of one or more characters Identified by its field name
Record Group of related fields Is contained in tables or data files
Primary key or key field Unique identifier for each record
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The Levels of Data in a Database
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Types of Database Programs
Two types of database programs, software used to create databases and use their data File management programs
Manage only one table or file Known as a flat file
Database management systems (DBMS)
Manage multiple tables or filesCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 40
Types of Database Programs
File management systems are: Useful for personal or small business
needs Used to develop an uncomplicated
computerized system for information storage and retrieval
Inexpensive and easy to use Unable to link to data stored in other
filesCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 41
Types of Database Programs
Database management systems (DBMS) are: Able to access, store, and edit data Available in a variety of forms Not usually tied to one particular platform Able to present information in various
formats
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Types of Database Programs
Database management systems (DBMS)
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Types of Database Programs
Database management system classifications Based on how information is organized and
retrieved Four main DBMS classifications
Flat Hierarchical Network Relational database management system (RDBMS)
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Types of Database Programs
Relational database management systems (RDBMS) Most widely used class of DBMS Link data found in several tables or
files Compared with file management
programs: More expensive Harder to learn Better in controlling data redundancy Better in preventing potential data errorsCopyright © 2009 Pearson Education, Inc. Publishing as Prentice
Hall 45
Types of Database Programs
Data warehouses Combine all the data of an
organization into one large database Help executives make decisions
Examine data through the drill-down method
View performance data for whole company
Search through individual department data
Data marts are similar but support a department or division
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Types of Database Programs
Data mining Method used for
data review and investigation
Can be used to determine unknown data patterns
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Types of Database Programs
Client/server database systems Use database server software that
reacts to the information requests of remote users
Also use database client software to provide an interface with the user
Use queries to request information from the database server
Examples: ATMs and online bankingCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 48
Types of Database Programs
Web-database integration involves taking database information and making it accessible over the Internet.
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Advantages of Database Management Systems
Characteristics of a good database: Data integrity Data independence Avoiding data redundancy Data security Data maintenance
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Advantages of Database Management Systems
Data within a database is considered to have data integrity if that data is considered valid.
Data validation techniques are used as an attempt to prevent data integrity errors.
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Advantages of Database Management Systems
Data independence Data that controls applications and
data stored in the database are kept separate.
Avoiding data redundancy Enter data only once. Multiple entry of the same data is a
sign of an inadequately developed system.
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Advantages of Database Management Systems
Data security: Prevents a database’s contents from being accessed by unauthorized users.
Data maintenance: Required to permit the proper care and protection of data.
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Information Systems: Tools for Global Competitiveness
A skillfully created information system: Integrates data, computer hardware,
software, procedures, and users Main functions include:
Accepting data Converting data into information Storing data Distributing the information
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Information Systems: Tools for Global Competitiveness
Methods for controlling information include: Only routing information
to appropriate users Summarizing information Ensuring information
selectivity Getting rid of needless
information that wastes time and resources
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 55
Information Systems: Tools for Global Competitiveness
Each of the core functions of an organization is managed by the appropriate functional division (functional unit, functional area).
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Information Systems: Tools for Global Competitiveness
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Functional divisions of an organization: Accounting and finance Marketing and sales Human resources Management Manufacturing Information systems
Information Systems in Organizations: A Survey
For retailers, computers and databases are no longer used solely for traditional applications.
Point of sales (POS) cash registers are computers that integrate credit card authorization and inventory systems and are used as marketing devices.
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 58
Information Systems in Organizations: A Survey
Other systems that retailers use include: Check-screening systems, which
determine if a check is written on a delinquent account
Signature capture systems, which obtain digital customer signatures
Photo checkout systems, which show the photo of a customer at the time a credit card is used
Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 59