System Analysis & Design Database Systems
1. Introduction
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A system is a set of interrelated elements (part, processes, components, functions) which operate together to achieve some objectives and common goals. Any system consist of:-
- Input system design
- Output system design
- Processing system design
A simple structure of the system can be though as in figure (1.1) below.
Figure (1.1) A simple System structure
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Input system design
Every system requires some form of input data. Where data consists of basic facts that are the
system’s raw material. There are several things must take in consideration:
- Define the input requirements
- Selecting input media
- Classify the data & design coding system
- Design the shape of input data
Output system design
The system process input data and produce information of a useful form of output. Where
information is a data that has been changed into a useful form of output. In output system
consideration:
- Define the output requirements
- Selecting output media
- Design the shape of output report specification
- Define the content of output reporting
Processing System Design
To have an accurate processing and get the desired result, the data must coded, this coding is essential in data processing for several reasons:
- Precise identification
- Storage spaces
- Data entry effort
- Fast access to stored data
- Flexibility
- Security
To achieve good coding the facilities bellow must gain:
- Unique
- Meaningful
- Processable
- Brief
- Sortrable
- Expantable
Feedback
It is a mechanism takes some of system output and feed back to the input system in order to control the system behavior to make its works can be done within control limits. To put the data under any request and not lost it a file mechanism must exist, this facility need to:
- Define and identify the file media
- Define and identify the organization and access methods
- Select the processing type
- File efficiency, no. of data processing when using the file at one time
- File size (capacity)
Analysis Process
1- Is the examination, identification, evaluation of components and interrelationship involved in the sys. from problem through maintenance and modification phases.
2- Is the study of problem prior to take any action.
Analysis Steps:
Sys. analysis depend on:
a. Sys and its environment.
b. Analyst experience and skills.
c. Collected facts.
So there are no standard rules for analysis for all cases but, there are general steps can followed:
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Examine the collected facts, and be sure these facts comprehensive (completeness) and correct.
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Classified these facts into their elements.
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Establish logical relationships between these elements.
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Suggest the proposed alternatives solutions to the current sys. and evaluate them.
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Choose the suitable alternative and identify its requirements.
Disadvantages of missing (ignoring) the analysis steps:
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Difficult to design the sys and may reach the case (over design) which lead to a high cost.
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The analyst may fail to discover the problem.
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= = = = = develop positive ideas.
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= = = = = identify the requirements of the new sys.
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= = = = = to evaluate and study the alternatives.
The successful analysis process should involve the following:
1- Select an optimal target.
2- Producing detailed documentation of the target in such a manner that subsequence implementation can be evaluated to see whether or not the target has been attained.
3- Producing accurate predications of the important parameters associated with the target including: cost, benefits, schedules and performance characteristics.
4- Obtaining concurrence on each of the items above from each of the affected parties
In analysis phase the sys analyst should begin by identifying the problem and other articles as follows:
1- Determine who the user are.
2- Determine how to gather information.
3- Collect and analyze the information.
4- State the problem.
5- Describe the current sys.
6- Quantify the cost associated.
7- Summarize the current sys. limitations and constraints.
8- Establish all preliminary objectives and requirements.
9- Formulate general alternatives solutions.
10- Do preliminary cost/benefit analysis for each solution.
11- Estimate time and cost involved to develop each alternatives detailed solutions.
12- Summarize finding and state weather the problem warrants further development analysis.
The Preliminary Study Phase
Preliminary study phase contain on:
- Problem definition.
- Objectives setting.
- Feasibility study.
- Plan.
· Problem definition.
v Structure organization as a function, as a management levels charts.
v Management ratio through years:
§ Stock ratio
§ Profile =
§ Sales =
§ Product =
v Historical background.
§ Policies
§ Decision type
§ Decision limiting
§ Decision reasons
v Staff opinions.
· Objectives setting
v Clearly defined
v Quantified
v Time constrained
v Obtainable objectives
· Feasibility study
v Economic conclude cost/benefits
v Technical conclude the H.W and people
Well done feasibility study enables the:-
1. Lack of top management support.
2. Failure to clearly specify problem objectives.
3. Over optimization.
4. Estimations errors.
5. Crash project.
6. The H.W approach.
The System Analyst Position
A systems analyst investigate, analyze, design, and maintains a company’s information systems to performs those tasks, a system analyst constantly interacts with users and managers within and outside the organization.
Responsibilities
· The systems analysts job overlaps business and technical issues. Analysts translates business requirements into practical Information Technology (IT) projects that meet the company’s needs.
· A system analyst plans projects, develops, schedules, and estimates costs.
· To keep managers and users informed an analyst conducts meetings, delivers, presentation, and writes memory reports, and documentation.
System Analyst Background
A systems analyst needs
- Understanding of business operations and processes, management, decision making, accounting, data processing tech.
- Solid technical knowledge in programming tech and languages, S.W, H.W, O.S.
System Analyst Skills
- Ability to understand the current sys. In details incomprehensive way in short time.
- Ability to think and analyze in a logic way
- Strong, oral & written communication skill
- Ability to deal with a different people
- Ability to work in a team
Fact-Finding Methods
There are various fact-finding techniques used for gathering information about the system under study, some of these are:
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Surveys and Questionnaires
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Although software can help the you to gather and analyze facts, no program actually performs fact-finding for you. The first step is to identify
The information you need.
Typically you begin by asking a series of questions, such as the following:
· What business functions are supported by the current system?
· What strategic objectives and business requirements must be supported by the new system?
· What are the benefits of the proposed?
· What information do users and managers need from the system?
· What transactions will the system process?
· What procedures, interfaces, and security?
· What risks are acceptable?
· What budget and timetable constraints will affect system development?
To obtain answers to the above questions you must start with fact-finding plan.
Fact-finding involves answers to five familiar questions who, what, when, where, why, and how.
Examples of these questions are:
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Who? Who performs each of the procedures within the system? Why? Are the correct people performing the activity? Could other people perform tasks more effectively?
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What? What is being done? What procedures are being followed?
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Where? Where are operations being performed? Why?
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When? When is a procedure performed? Why is it performed at this time?
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How? How is a procedure performed? Why is it being performed at this time?
Interviews
System analyst spends great deal of time taking with people, both inside and outside the information technology department.
The interviews are an important fact-finding technique. It is a planned meeting during which you obtain information from people.
The analyst must have skills needed to plan, conduct, and document interviews successfully.
The interviewing process consists of the following steps:
1. Determine the people to interview.
2. Establish objectives for the interview.
3. Develop interview questions.
4. Prepare for the interview.
5. Conduct the interview.
6. Document the interview.
7. Evaluate the interview.
Document Review
Document review can help you to understand how the current system is supposed to work. You should review all the system documentation , which include technical documentation and operations manual such as user guide , also include the software package documentation if any.
Observation
The observation of the current operating procedures is another fact-finding technique. It gives you a better understanding of system procedures.
During the observation you have to do the following:
1. Observe all the steps in a transaction and note the documents, inputs, outputs, and process involved.
2. Examine each form, record, and report.
3. Consider each user who works. Determine the purpose of each item of information serves.
4. Talk to the people who receive current reports to see whether the reports are complete, timely, accurate, and in useful form.
Questionnaires and Surveys
A questionnaire is a document containing a number of standard questions that can be send to many individuals. Questionnaires are used to obtain information about workloads, reports received, volumes of transactions handled, typed of job duties, difficulties, and opinions, of how the job could be performed better or more efficiently.
A typical questionnaire starts with a heading , which includes a title , a brief statements, of purpose, the name and telephone number of the contact persons, the deadline date for completion , and how and where to return the form.
The heading usually is followed by general instruction that provide clear guidance on how to answer the questions. Also the questionnaires contain conclusion that thanks the participants and reminds them how to return the form. Figure (2.1) show example of questionnaire.
Sampling
1. When studying an information system you should collect example of actual documents using a process called sampling. The sample might include records, reports, operational logs, data entry documents, and various types of forms. There are many methods of sampling such as:
· Systematic sample العينة المنتظمة
· Stratified sample العينة المتحيزة
· Random sample العينة العشوائية
The main objective of sample is to ensure that it represents the overall population accurately.
You may consider sampling when using interviews or questionnaires.
Research
Research is another important fact-finding technique.
Your research can include reviewing journals, periodicals, and books to obtain background information, technical material, and news about industry trends and developments. The Internet is an extremely valuable research tool. Most major hardware and software vendors maintain sites on the Web where you can obtain information about products and services offered by the company.
Impact of Computer System on Organization
- Use data never available before
- Centerlized files
- Quality of data or information
- Ability to monitor and control
- Wide span of control
- Reduce time needed to carry out the functions
- Attention to exception
A Computer-Based Information Database System
· Today any organization small or large gain as much as possible from what computer and communication technologies represented.
· Also information became vital resource to any organization. Therefore database information system is very important project to all business, and government organizations.
An information system can be any organized combination of people, hardware, software, communications networks, and data resources (Databases), that collect, transforms, and disseminates information in an organization, see figure (1.2).
Figure (1.2) A computer-based information database system
The System Life Cycle
Computer-based information systems are developed in a sequence of steps. This sequence is known as the system life cycle or the problem-solving cycle. The system life cycle is used for several reasons:
1. It is used to organize the large number of activities needed to build the system.
2. It helps the analysts, and designers, to solve problems that are faced during the system development.
3. It assists management by producing reports on project status and keeping track of resource needs.
Figure (1.3) and Figure (1.4) illustrate the system life cycle.
Figure (1.3) The system life cycle
System
Maintenance
Product:
Improved
System
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System
Analysis
Product:
Functional
Requirements
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System
Implementation
Product:
Operational
System
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System
Design
Product:
System
Specifications
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System
Investigation
Product:
Feasibility
study
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Figure (1.4) system life cycle steps
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .