SAD Summary 2007 - Eonzerimar

8/8/2019 SAD Summary 2007 - Eonzerimar

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Chapter 1

1. An information system is an arrangement of people, data, process, information presentation,and information technology that interact to support and improve the operations in a business

and to support the problem-solving and decision-making needs of management and users.

2. Information technology is a contemporary term that describes the combination of computertechnology (hardware and software) with telecommunications technology (data, image, and

voice networks).

3. Information workers are the stakeholders in information systems. Information workers includethose people whose jobs involve the creation, collection, processing, distribution, and use of

information. They include:

a. System owners the sponsors and chief advocates of information system.

b. System users the people who use or are affected by the information system on a

regular basis. Geographically, system users may be internal, mobile, remote, or external.

c. System designers technology specialists who translate system users' business

requirements and constraints into technical solutions.

d. System builders technology specialists who construct the information system

components based on the design specifications.

e. Systems analysts the people who facilitate the development of information systems

and computer applications. They coordinate the efforts of the owners, users, designers, andbuilders. Frequently, they may play one of those roles as well. Systems analysts perform

system analysis and design.

i) Systems analysis is the study of a business problem domain to recommend

improvements and specify the business requirements for the solution.

ii) Systems design is the specification or construction of a technical, computer-based

solution for the business requirements identified in a systems analysis.

f. Information technology vendors and consultants the people who bring external

expertise, experience, and human resource capacity to many projects.

4. The systems analyst facilitates most of the activities to develop or acquire an informationsystem. A systems analyst studies the problems and needs of an organization to determine how

people, data, process, communication, and information technology can best accomplish

improvements for the business.

5. A business analyst is a systems analyst that specializes in business problem analysis andtechnology-independent requirements analysis.


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6. Most systems analysts work for the systems development group in the information servicesgroup or department of a business. Alternatively systems analysts (under different titles) work

for IT consulting firms, outsources, and application software vendors.

7. Players in the information systems game are being affected by a number of business andtechnology trends including:

a. Total quality management, a comprehensive approach to facilitating quality

improvements and management within a business.

b. Business process redesign, the study, analysis, and redesign of fundamental business

processes to reduce costs and/or improve value added to the business.

c. Continuous process improvement, the continuous monitoring of business processes to

effect small but measurable improvements to cost reduction and value added.

d. The year 2000 compatibility problem and the Euro currency conversion directive.

e. Enterprise resources planning, the selection and implementation of a single vendor's

fully integrated information system that spans most basic business functions required by a

major corporation.

f. Electronic commerce, a new way of doing business that involves conducting both

internal and external business over the Internet, intranets, and extranets.

8. The system analyst is a principal player in the information systems game. To prepare for acareer as a systems analyst you will need to gain:

a. A current working knowledge of information technology, which you must keep current.

b. Some computer programming experience and expertise.

c. General business knowledge and, if possible, business experience.

d. Better than average problem-solving skills.

e. Better than average interpersonal communication skills.

f. Strong interpersonal relations and teamwork skills.

g. Flexibility and adaptability to change as the problem and politics of business change.

h. Good character and strong ethics, necessary because analysts gain access to sensitive and

confidential data, facts, and opinions.

i. Systems analysis and design skills-the subject of this book!

9. Prospects for a career as a systems analyst look bright through 2006 and beyond. A shortage ofanalysts will fuel the prospects for those experienced analysts who have remained current with


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the fast-changing world of information technology.


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Chapter 2

1. Data are raw facts about a business and its business transactions. Information is data that hasbeen refined and organized by processing and purposeful intelligence.

2. An information system (IS) is an arrangement of people, data, processes, interfaces, andcommunications that interact to support and improve day-to-day operations in a business as

well as support the problem-solving and decision-making needs of management and users.

a. Information systems are enabled by information technology, a contemporary-term that

describes the combination of computer technology (hardware and software) with

telecommunications technology (data, image, and voice networks).

b. Front-office information systems support business functions that reach out to customers

(or constituents).

c. Back-office information systems support internal business operations as well as interact

with suppliers (of materials, equipment, supplies and services).

3. Information systems fulfill one or more of the following basic purposes:a. Transaction processing systems capture and process data about (or of) business

transactions.

b. Management information systems provide essential management reports required to

plan, monitor, and control business operations.

c. Decision support systems provide users, especially managers, with decision-oriented

information in response to various unstructured decision and problem-solving opportunities.

(1) Decision support systems are built around data warehouses read-only,

informational databases that are populated with detailed, summary, and exception data

and information that can be accessed by end-users and managers with DSS tools that

generate a virtually limitless variety of information in support of unstructured decisions.

d. Expert systems capture and simulate the knowledge and expertise of subject matter

experts so non-experts may apply it.

e. Office automation (OA) systems support the wide range of business office activities that

provide for improved work flow and communications between workers, regardless of

whether or nor those workers are located in the same office.

(1) Personal information systems are those designed to meet the needs of a single user.

They are designed to boost an individual's productivity.

(2) Work group information systems are those designed to meet the needs of a work


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group. They are designed to boost the group's productivity.

4. Information systems architecture provides a unifying framework into which various people withdifferent perspectives can organize and view the fundamental building blocks of information

systems. The framework used throughout this book is based on, and adapted from, the Zachman

Framework for Information Systems Architecture.

a. The information system framework is visually presented as a matrix. The rows

correspond to the perspectives of different stakeholders in the information system

development process. The columns correspond to a specific focus or dimension of the

information system that must be analyzed, designed, and implemented. Each cell represents

one perspective and one focus.

b. Although the cells can be studied and developed in isolation, they must be synchronized

with the other cells (both across rows and down columns) to develop a successful

information system.

5. The six perspectives are provided by:a. System owners, who pay for the system to be built and maintained. They own the system,

set priorities for the system, and determine policies for its use.

b. System users, who actually use the system to perform or support the work to be

completed. System users define the business requirements and performance expectations for

the system to be built.

c. System designers, the technical specialists who design the system to meet the user's

requirements.In many cases, system designers may also be system builders.

d. System builders, the technical specialists who construct, test, and deliver the system into

operation.

e. Systems analysts, who facilitate the development of information systems and computer

applications by bridging the communications gap that exists between nontechnical system

owners and users technical system designers and builders.

f. IT vendors and consultants, who sell hardware, software and services to businesses for

incorporation into their information systems.

6. The three focuses represented in the model are:a. DATA the raw material used to create useful information.

b. PROCESSES the activities (including management) that carry out the mission

of the business.

c. INTERFACES how the system interfaces with its users and other information

systems.


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software.

2. The Capability Maturity Model (CMM) is a framework to assess the maturity level of anorganization's information system development and management processes and products. It

consists of five levels of measured by a set of guidelines called the key process areas.

a. Level 1 I

nitial: This is sometimes called anarchy or chaos.

b. Level 2 Repeatable: Project management processes and practices are established to

track project costs, schedules, and functionality.

c. Level 3 Defined: A standard systems development process (sometimes called a

methodology) is purchased or developed and integrated throughout the information

systems/services unit of the organization.

d. Level 4 Managed: Measurable goals for quality and productivity are established.

e. Level 5 Optimizing: The standardized systems development process is continuously

monitored and improved based on measures and data analysis established in level 4.

3. A system life cycle divides the life of an information system into two stages, systemsdevelopment and systems operation and supportfirst you build it; then you use it.

A systems development methodology is a very formal and precise system development process

that defines a set of activities, methods, vest practices, deliverables, and automated tools that

system developers and project managers use to develop and maintain information systems and

softwares.

4. The following principles should underlie all systems development methodologies:a. Get the owners and users involved.

b. Use a problem-solving approach.

c. Establish phases and activities.

d. Establish standards.

e. Justify systems as capital

investments.

f. Don't be afraid to cancel or revise

scope.

g. Divide and conquer.

h. Design systems for growth and

change

.

5. System development projects are triggered by problems, opportunities, and directives.a. A problem is an undesirable situation that prevents the organization from fully achieving

its purpose, goals, and/or objectives.

b. An opportunity is a chance to improve the organization even in the absence of specific

problems.


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c. A directive is a new requirement that's imposed by management, government, or some

external influence.

6. Wetherbe's PIECES framework is useful for categorizing problems, opportunities, anddirectives. The letters of the PIECES acronym correspond to Performance, Information,

Economics, Control, Efficiency, and Service.

7. Traditional, basic systems development phases include:a. Preliminary investigation.

b. Problem analysis.

c. Requirements Analysis.

d. Decision analysis.

e. Design.

f. Construction.

g. Implementation.

8. Cross life cycle activities are activities that overlap many or all phases of the methodology.They may include:

a. Fact-finding

The formal process of using research, interviews, meetings, questionnaires, sampling,

and other techniques to collect information about systems, requirements, and preferences.

b. Documentation

The activity of recording facts and specification for a system for current and future

reference. Documentation is frequently stored in a repository, a database where system

developers store all documentation, knowledge, and products for one or more information

systems or projects.

c. Presentation

The activity of communicating findings, recommendations, and documentation for

review by interested users and managers. Presentations may be either written or verbal.

d. Feasibility analysis

The activity by which feasibility, a measure of how beneficial the development of an

information system would be to an organization, is measured and assessed.


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scratch or from templates. The resulting models are subsequently transformed into

program code.

(3) Reverse engineering allows a CASE tool to read existing program code and

transform that code into a representative system model that can be edited and refined by

the systems analyst.

b. Application development environments (ADE's) are integrated software development tools

that provide all the facilities necessary to develop new application software with maximum speed and

quality.

c. Process management tools to help us document and manage a methodology and routes, itsdeliverables, and quality management standards.

d. Project management tools help us plan system development activities (preferably using theapproved methodology), estimate and assign resources (including people and costs), schedule

activities and resources, monitoring progress against schedule and budget, control and modify

schedule and resources, and report project progress.


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Chapter 4

1. A project is a (temporary) sequence of unique, complex, and connected activities having onegoal or purpose and that must be completed by a specific time, within budget, and according to

specification.

2. Project management is the process of scoping, planning, staffing, organizing, directing, andcontrolling the development of an acceptable system at a minimum cost within a specified time

frame.

3. Process management is an ongoing activity that documents, manages the use of, and improvesan organization's chosen methodology (the process) for systems development. Process

management is concerned with the activities, deliverables, and quality standards to be applied

to all projects.

4. From a project management perspective, a project is considered a success if the resultinginformation system is acceptable to the customer, the system was delivered on time and

within budget, and the system development process had a minimal impact on ongoing

business operations.

5. The Project Management Institute has created the Project Management Body of Knowledge(PMBOK) for the education and certification of professional project managers. It addresses:

a. Project manager competencies.

b. Project management functions, which include:

i) Scoping v) Organizing

ii) Planning vi) Directing

iii) Estimating vii) Controlling

iv) Scheduling viii) Closing

c. Tools and techniques such as:

i) P ERT charts, graphical network models that depict a project's tasks and the

relationships between those tasks.

ii) Gantt charts, simple horizontal bar charts that depict project tasks against a calendar.

d. Project management software.

6. Project management is a cross life cycle activity; that is, project management tasks thatoverlap all the system development phases. A project management process is essential to

achieving CMM Level 2 maturity.


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7. Joint project planning (JPP) is a strategy wherein all stakeholders in a project participate in aone-to-three-day project management workshop, the result of which is consensus agreement on

project scope, schedule, resources, and budget.

8. The tasks of project management include:a.

N

egotiate scope. Scope defines the boundaries of a project and is included in thestatement of work, a narrative description of the work to be performed as part of a project.

b. Identify tasks. A work breakdown structure (Wbs) is a hierarchical decomposition of the

project into its tasks and subtasks. Some tasks represent the completion of milestone or the

completion of major deliverables during a project.

c. Estimate task durations. There are many techniques and tools for estimating task

durations.

d. Specify intertask dependencies. The start or completion of individual tasks may be

dependent on the start or completion of other tasks. These dependencies impact thecompletion of any project.

i) Forward and reverse scheduling are two strategies for generating the preliminary

schedule. The former works forward from a project start date, while the latter works

backward from a project deadline.

e. Assign resources. The following resources may impact a project schedule: People,

services, facilities and equipment, supplies and materials, and money.

i) Such resources must be assigned to tasks to develop a schedule.

ii) Resource leveling is a strategy used to correct resource over-allocations by some

combination ofdelayingorsplitting tasks. Resource leveling requires knowledge of:

(1) The critical path that sequence of dependent tasks that have the largest sum of

most likely durations. The critical path determines the earliest possible completion

date of the project.

(2) Slack time the amount of delay that can be tolerated between the starting time

and completion time of a task without causing a delay in the completion date of the

entire project.

f. Direct the team effort. One of the most important dimensions of directing the team effort

is the supervision of people.

g. Monitoring and control progress. During the project, the project manager must monitor

project progress against the scope, schedule, and budget, and when necessary, make

adjustments scope, schedule, and resources.

i) Progress reporting is an essential control process that uses communication to keep a


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project within scope, on time, and within budget.

ii) A complete project plan provides mechanisms and a process to manage requests for

changes to scope. This is called change management.

iii) Change management frequently requires a project manager to manage the

expectations of user management and users themselves. An expectations managementmatrix is a rule-driven tool for helping management understand the dynamics and

impact of changing project parameters such as cost, schedule, scope, and quality.

iv) Schedule adjustments are required when a project's scope changes, or when other

factors drive schedule or budget out of the projected range.

h. Assess project results and experiences. This final activity involves soliciting feedback

from project team members (including customers) concerning their project experiences and

suggestions aimed at improving the project and process management of the organization.

Chapter 5

1. Formally, systems analysis is the dissection of a system into its component pieces. As a


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problem-solving phase, it precedes systems design. With respect to information systems

development, systems analysis is the preliminary investigation of a proposed project, the study

and problem analysis of the existing systems, the requirements analysis of business

requirements for the new system, and the decision analysis for alternative solutions to fulfill the

requirements.

2. The results of systems analysis are stored in a repository for use in later phases and projects.3. There are several popular or emerging strategies for systems analysis. These techniques can be

used in combination with one another.

a. Model-driven analysis techniques emphasize the drawing of pictorial system models

that represent either a current reality or a target vision of the system.

1) Structured analysis is a technique that focuses on modeling processes.

2) Information engineeringis a technique that focuses on modeling data.

3) Object-oriented analysis is a technique that focuses on modeling objects that

encapsulate the concerns of data and processes that act on that data.

b. Accelerated analysis approaches emphasize the construction of working models of a

system in an effort to accelerate systems analysis.

1) Discovery prototypingis a technique that focuses on building small-scale, functional

subsystems to discover requirements.

2) Rapid architecture analysis attempts to automatically generate system models from

either prototypes or existing systems. The automatic generation of models requiresreverse engineering technology.

c. Both model-driven and accelerated system analysis approaches are dependent on

requirements discovery techniques to identify or extract problems and requirements from

system owners and users.

1 ) Fact-findingis the formal process of using research, interviews, questionnaires,

sampling, and other techniques to collect information.

2) Joint requirements planning (JRP) techniques use facilitated workshops to bring

together all interested parties and accelerate fact-finding.

d. Business process redesign focuses on simplifying and streamlining fundamental

business processes before applying information technology to those processes.

4. Each phase of system analysis (preliminary investigation, problem analysis, requirementsanalysis, and decision analysis) can be understood in the context of the information system

building blocks: DATA, PROCESS, and INTERFACES.


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5. The preliminary phase determines the worthiness of the project and creates a plan to completethose projects deemed worthy of a detailed study and analysis. To accomplish the preliminary

investigation phase, the systems analyst will work with the systems owners and users to:

(a) list problems, opportunities, and directives;

(b) negotiate preliminary scope;

(c) assess project worth;

(d) plan the project, and

(e) present the project to the businesscommunity.

The deliverable for the preliminary investigation phase is a project charter that must be approved by

system owners and/or a decision-making body, commonly referred to as the steering committee.

6. The purpose of the problem analysis phase is to answer the questions: Are the problems reallyworth solving? And Is a new system really worth building? To answer these questions, the

problem analysis phase thoroughly analyzes the alleged problems and opportunities first

identified in the preliminary investigation phase. To complete the problem analysis phase, the

analyst will continue to work with the system owner, system users, and other IS management

and staff. The systems analyst and appropriate participants will:

(a) study the problem domain;

(b) thoroughly analyze problems and

opportunities,

(c) optionally, analyze business processes;

(d) establish system improvement objectives

and constraints;

(e) update the project plan; and

(f) present the findings and recommendations.

The deliverables for the problem analysis phase are the system improvement objectives.

7. The requirements analysis phase identifies what the new system is to do without theconsideration of technology; in other words, define the business requirements for a new system.

As in the preliminary investigation and problem analysis phases, the analyst actively works wih

system users and owners as well as other IS professionals. To complete the requirements

analysis phase, the analyst and appropriate participants will:

(a) define requirements;

(b) analyze functional requirements using

system modeling and/or discovery

prototyping;

(c) trace and complete the requirements

statements;

(d) prioritize the requirements; and

(e) update the project and scope.

The deliverable of the requirements analysis phase is the business requirements statement. Because

requirements are a moving target with no finalization, requirements analysis also includes an

ongoing task to manage changes to the requirements.

8. The purpose of the decision analysis phase is to transition the project from business concerns totechnical solutions by identifying, analyzing, and recommending a technical system solution.

To complete the decision analysis phase, the analyst and appropriate participants will:


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(a) define candidate solutions;

(b) analyze candidate solutions for feasibility (technical, operational, economic, and schedule

feasibility);

(c) compare feasible candidate solutions to select one or more recommended solutions;

(d) update the project planbased on the recommended solution; and

(e) present and defend the target solution.

The deliverable of the decision analysis phase is the system proposal.


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Chapter6

1. System requirements define the services the system the system is to provide and prescribeconstraints for its operation. In documenting the system requirements for a new information

system, an analyst will likely identify dozens of unique requirements. To simplify the presentation of the requirements and to make them more readable, understandable and

traceable, requirements are often categorized asfunctional versus nonfunctional.

2. For systems analysts to be successful, they must be skilled in problem analysis. This is theability to identify problems, understand the problems (including the causes and effects), and

understand any constraints that limit the solution. A popular tool used by development teams to

identify, analyze and solve problems is an Ishikawa diagram.

3. Effective fact finding techniques are crucial to the applications of systems analysis and designmethods during systems projects. Fact finding is performed during all phases of the systems

development life cycle. To support development activities, the analyst must collect facts about

end users, the business, data and information resources, and information systems components.

4. Conducting business in an ethical manner is a required practice, and analysts need to be moreaware of the implications of not being ethical.

5. Fact finding activities usually produce requirements that conflict with each other. This isbecause requirements are solicited from many different sources and each person has his own

opinions and the desire to the functionality and features of the new system. Systems analysts

perform requirements analysis to discover and resolve the problems with the requirements and

reach agreement on any modifications to satisfy the stakeholders.

6. System requirements are usually documented in aformalway to communicate the requirementsto the key stakeholders of the system. This document usually serves as the contract between the

system owners and the development team on what is going to be provided in terms of a new

system.

7. Over the lifetime of the project it is very common for new requirements to emerge and existingrequirements to change once a requirements definition document has been approved.

Requirements management encompasses the policies, procedures, and processes that govern

how a change is handled.

8. There are seven fact finding technique.a. The sampling of existing documents and files can provide many facts and details with little

or no direct personal communication being necessary. The analyst should collect historical

documents, business operations manuals and forms, and information systems documents.

b. Research is an often overlooked technique based on the study of other similar


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applications. It now has become more convenient with the Internet and World Wide Web.

Site visits are a special form of research.

c. Observation is a fact finding technique in which the analyst studies people doing theirjobs.

d.

Questionnaires are used to collect similar facts from a larger number of individuals.

e. Interviews are the most popular but the most time consuming fact finding technique.When interviewing, the analyst meets individually with people to gather information.

1) When most people talk about communication skills they think of speaking and writing,but the skills of listening may be the most important, especially during the interviewing

process.

2) Research has determined that of a persons total feelings, only 7 percent arecommunicated verbally (in words), 38 percent are communicated by the tone of voice

used, and 55 percent are communicated by facial and body expressions. If you onlylisten to someones words, you are missing most of what they have to say! Experienced

systems analysts pay close attention to body language and proxemics.

f. Discovery prototyping is frequently applied to systems development projects, especiallywhen the development team is having problems defining system requirements. The

philosophy is that the users will recognize the requirements when they see them. It is

important that the prototype be developed quickly so it can be used during the development

process.

g. Many analysts find flaws with interviewing separate interviews often lead to conflictingfacts, opinions and priorities. The end result is numerous follow up interviews and / or

group meetings. For this reason, many organizations used the group work session known as

a joint requirements planning as a substitute for interviews.

1) Joint requirements planning sessions include a variety of participants and roles. Eachparticipant is expected to attend and actively participate for the entire duration of the

JRP session.

2) An effective JRP session involves extensive planning. Planning for a JRP sessioninvolves three steps: selecting a location, selecting JRP participants and preparing an

agenda.

9. Because time is money, it is wise and practical for the system analyst to use a fact findingstrategy to maximize the value of time spent with the end users.

10.Systems analysts should assemble or document the information they have gathered in anunderstandable and meaningful way. Good systems analysts used techniques and tools that

allow them to clearly specify the system requirements.


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a. Use cases describe the system functions from the perspective of external users and in amanner and terminology they understand.

b. Many organizations have complex policies and decision making rules that drive their business processes. Decision tables are a popular tool in expressing and analyzing these

requirements.

c. Many organizations document their requirements in tabular form called a requirementstable.


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Chapter 7

1. A model is a representation of reality. Models can be built for existing systems as a way to better understand those systems or for proposed systems as a way to document business

requirements or technical designs.

a. Logical models document the business requirements to show what a system is or does.They are implementation independent; that is, they depict the system independent of any

technical implementation. As such, logical models illustrate the essence of the system.

b. Physical models show not only what a system is or does, but also how the system isphysically and technically implemented. They are implementation dependent because they

reflect technology choices and the limitations of those technology choices.

2. Data modeling is a technique for organizing and documenting a systems DATA. Datamodeling is sometimes called database modeling because a data model is usually implementedas a database.

3. There are several notations for data modeling. The actual model is frequently called an entityrelationship diagram (ERD) because it depicts data in terms of the entities and relationships

described by the data.

4. An entity is something about which the business needs to store data. Classes of entities include:persons, places, objects, events or concepts.

5. An entity instance is a single occurrence of an entity class.6. Pieces of data we want to store about each instance of a given entity are called an attribute. An

attribute is a descriptive property or characteristic of the entity. Some attributes can be logically

grouped into super attributes called compound attributes.

7. When analyzing a system, we should define those values for an attribute that are legitimate orthat make business sense. The values for each attribute are defined in terms of three properties:

data type, domain and default.

a. The data type defines what class of data can be stored in that attribute.b. The domain of an attribute defines what values an attribute can legitimately take on.c. The default value for an attribute is the value that will be recorded if not specified by the

user.

8. Every entity must have an identifier or key. A key is an attribute, or a group of attributes, thatassumes a unique value for each entity instance.

a. Group of attributes that uniquely identifies an instance of an entity is called a concatenated


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key.

b. A candidate key is a candidate to become the primary identifier of instances of an entity.c. A primary key is the candidate key that will most commonly be used to uniquely identify a

single entity instance.

d. Any candidate key that is not selected to become the primary key is called an alternate key.e. Sometimes, it is also necessary to identify a subset of entity instances as opposed to a single

instance. A sub setting criteria is an attribute (or concatenated attribute) whose finite

values divide all entity instances into useful subsets.

9. A relationship is natural business association that exists between one or more entities. Therelationship may represent an event that links the entities or merely a logical affinity that exist

between the entities. All relationships are implicitly bidirectional, meaning they can be

interpreted in both directions.

10.Cardinality defines the minimum and maximum number of occurrences of one entity for asingle occurrence of the related entity. Because all relationships are bidirectional, cardinality

must be defined in both directions for every relationship.

11.The degree of a relationship is the number of entity classes that participate in the relationship.Not all relationships are binary. Some relationships may be recursive relationships wherein the

relationship exists between different instances of the same entity. Relationships also exist

between more than two different entities, as in the case of a 3 ary or ternary relationship.

12.An associative entity is an entity that inherits its primary key from more than one other entity(parents). Each part of that concatenated key points to one and only one instance of each of theconnecting entities.

13.Foreign key is a primary key of one entity that is contributed to (duplicated in) another entityto identify instances of a relationship. A foreign key (always in a child entity) always matches

the primary key (in a parent entity)

14.Non - identifying relationships are those in which each of the participating entities has its ownindependent primary key, of which none of the primary key attributes is shared. The entities in

a non identifying relationship are referred to asstrongor independent entities because neither

depends on any other entity for its identification. Identifying relationships are those in whichthe parent entity contributes its primary key to become part of the primary key of the child

entity. The child entity of any identifying relationship is referred to as a weakentity because its

identification is dependent on the existence of the parent entitys existence.

15.A nonspecific relationship (or many to many relationship) is one in which many instances ofone entity are associated with many instances of another entity. Such relationships are suitable

only for preliminary data models and should be resolved as quickly as possible.


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16.Generalization is an approach that seeks to discover and exploit the commonalities betweenentities. It is a technique wherein the attributes are grouped to form entity super types and

subtypes.

17.A logical data model is developed in the following stages:a.

Entities are discovered and defined.

b. A context data model is built. A context data model contains only business entities andrelationships identifies by the system owners and users.

c. A key based data model is built. The key based model eliminates nonspecificrelationships and adds associative entities. All entities in the model are given keys.

d. A fully attributed model is built. This model shows all the attributes to be stored in thesystem.

e. A fully described model is built. Each attribute is defined in the dictionary and described interms of properties such as domain and security.

f. The completed data model is then analyzed for adapt ability and flexibility through aprocess called normalization. The final analyzed model is referred to as third normal form

data model.

18.A logical data model does not communicate data requirements on a business operating locationbasis. Systems analysts have found it useful to define these requirements in the form of a data

to location CRUD matrix.

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SAD Summary 2007 - Eonzerimar