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Management Information System and Decision Support System Semiester - 3 Kolhan University Sandeep Ghatuary

Management Information System and Decision Support System

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Page 1: Management Information System and Decision Support System

Management Information

System and Decision Support

System Semiester - 3

Kolhan University

Sandeep Ghatuary

Page 2: Management Information System and Decision Support System

Management Information System and Decision Support System 2

Management Information System It is combination of three words i.e. Management, Information and System. To understand the concept MIS, we try to

understand these three words.

1. Management: “Management is the art of getting things done through and with the efforts of other people.”

However, a manager gets things done by performing basic managerial functions. These functions are: Planning,

Organizing, Staffing, Directing and Controlling.

2. Information: It is the second component of ‘MIS’. Information is a data which is processed and presented to

decision makers and helps them in making decisions.

3. System: The word ‘System’ is a set of elements that are inter-related and interdependent to achieve a common

goal.

MIS: Definition:

1. Management, Information and System, it has been cleared that decision making is an important part of

managerial functions. For taking adequate decisions, Management Information (MI) is necessary as it works as

a vital input.

2. A system which consists of people, machines, procedures, databases and data models as its components is

known as Management Information System. This system collects data from external and internal sources of an

organization, analyses it and supplies management information to managers and helps them in making

decisions. MIS follows the system approach in which output is greater than the sum total of input.

3. According to G.B. Davis, “MIS is a man or machine that provides information to support management in

decision making process.”

Nature of MIS 1. Report orientation: Through MIS, every individual can perform their duty and the system automatically

produces performance reports to send for evaluation to the next level of hierarchy according to the

company and system specifications and / or requirements.

2. Action oriented: MIS performs regulating and scheduled actions on behalf of the user as the system is

customized on the basis of need and requirements at the user’s end.

3. Expectation oriented: The reports and automatic transactions are expected from a CBS (Computer Based

System).

4. Database oriented: Almost every MIS software is based on a Database backbone to support efficient storage

and retrieval of data to and from the system respectively simultaneously and concurrently from more than one

workstation at a time.

5. End-user oriented: Main emphasis is given on the end-user, who uses the system. The system must be

understandable and easy to access for the end user for a seamless operation of the system.

Framework of MIS / Needs to have MIS 1. Input of MIS

� Strategic plan or corporate policies

� Contains major financial objectives and often projects financial needs.

� Transaction processing system (TPS)

� Important financial information collected from almost every TPS - payroll, inventory control,

order processing, accounts payable, accounts receivable, general ledger.

� External sources

� Annual reports and financial statements of competitors and general news items.

2. Output of MIS

� Scheduled reports

� Produced periodically, or on a schedule (daily, weekly, monthly)

� Key-indicator report

� Summarizes the previous day’s critical activities

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Management Information System and Decision Support System 3

� Typically available at the beginning of each day

� Demand report

� Gives certain information at a manager’s request

� Exception report

� Automatically produced when a situation is unusual or requires management action.

MIS Functions:- � Data is collected from various internal and external sources. Collected data may be manual or computerized.

� Then data is processed.

� Information is stored for future use.

� Stored information is retrieved by users when required.

Characteristics of MIS:-

� The information system follows the system’s approach to study the system and its performance in the light of

purpose for which it has been developed.

� MIS is management oriented.

� MIS is designed according to the information needs of managers at different levels i.e. strategic planning level,

management control level and operational control level.

� MIS is future oriented.

� Integration is essential for MIS because of its ability to produce meaningful information.

� In MIS, common data flows provide an opportunity to avoid data redundancy, joining similar functions, data

storage and retrieval process, wherever possible. The constitution of common data flows is economically and

logically sound concept.

� Long Term Planning is involved for developing MIS.

� MIS is a sub system concept.

� MIS is computerized.

� MIS is user friendly.

Decision making process Decision making can be hard. Almost any decision involves some conflicts or dissatisfaction. The difficult part

is to pick one solution where the positive outcome can outweigh possible losses. Avoiding decisions often seems easier.

Yet, making your own decisions and accepting the consequence is the only way to stay in control of your time, your

success, and your life.

1. Decision under Certainty - We say that the decision is taken under certainty if each action is known to lead

invariably to a specific outcome (prospect, alternative, etc.).When the decision maker knows with reasonable

certainty about what the available alternatives are, and what conditions are associated with each alternative;

then a state of certainty is said to exist. For example, Air India needs to buy ten jumbo jets. The decision is

from whom to buy. Air India has two choices: McDonnell Douglas, and Airbus. Each of these companies is

known for their quality products. Air India can choose from any of these alternatives. Here, for making the

choice, there is less ambiguity and there is a relatively lower chance of making a bad decision.

2. Decision under Risk - We say that the decision is taken under risk if each action leads to one of a set of possible

specific outcomes, each outcome occurring with a known probability. In some situations, a manager is able to

estimate the level of probability at which certain variables could occur. The ability to estimate may be due to

experience, incomplete but reliable information or, in some cases, an accurate report. When estimates are

made, a degree of risk is involved. However some amount of information about the situation is available. The

situation requires estimating the probability that one or more known variables might influence the decision

being made.

3. Decision under Uncertainty - We say that the decision is taken under uncertainty if either action has as its

consequence a set of possible specific outcomes, but the probabilities of these outcomes are completely

unknown or are not even meaningful. A condition of uncertainty exists when a manager is faced with

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reaching a decision with no historical data concerning the variables and/or unknowns and their probability of

occurrence. For instance, the decision to introduce Kellogg corn flakes in India was made under

uncertainty.

� Modern Approach to Decision Making Under Uncertainty - Modern approach to decision making under

uncertainty helps in improving the quality of decision making. For making such decisions, there are three

approaches: risk analysis, decision trees and preference theory.

� Risk analysis : Risk analysis involves knowledge of the size and the nature of the risk involved,

in choosing a particular course of action. Before the launch of its Versa model, Maruti, conducted risk

analysis in the areas of capital investment, cost of production and pricing.

� Decision trees: A graphical representation of alternative courses of action with the possible outcomes

comprises a decision tree. It depicts the various decision points, chances, events and probabilities

involved in various decision- courses that might be undertaken.

� Preference or utility theory: This theory is based on the notion that individuals' attitudes towards risk

will vary. Some individuals are willing to take risk (gamble), whereas others are not willing to take risk

or take only low risk (risk averters). Managers play both these roles, when they are uncertain about the

outcome.

SIMON'S MODEL OF DECISION MAKING Herbert A. Simon developed a model of decision making. The model consisted of three steps, intelligence, design, and

choice. In the intelligence phase, the problem is identified, and information is collected concerning the problem. This

can be a long process, as the decision to be made comes from the information. The design phase develops several

possible solutions for the problem. Finally, the choice phase chooses the solution.

1. The Intelligence Phase - The intelligence phase consists of finding, identifying, and formulating the problem or

situation that calls for a decision. This has been called deciding what to decide. The intelligence stage may

involve, for example, comparing the current status of a project or process with its plan. The end result of the

intelligence phase is a decision statement. The name of this phase, “intelligence,” can be confusing.

Intelligence as we usually use the term informally, is talking about decision making, it is what we use after we

know a decision must be made. Simon borrowed the term from its military meaning, which involves the

gathering of information without necessarily knowing what it will lead to in terms of decisions to be made. In

business decision making, we must often collect a great deal of information before we realize that a decision is

called for.

2. The Design Phase- The design phase is where we develop alternatives. This phase may involve a great deal of

research into the available options. During the design phase we should also state our objectives for the decision

we are to make.

3. The Choice Phase - In the choice phase, we evaluate the alternatives that we developed in the design phase

and choose one of them. The end product of this phase is a decision that we can carry out.

Extensions to Simon's Model

4. Implementation - The decision that is ultimately carried out.

5. Review - In this phase, decision implemented is evaluated. Was the course of action taken a good choice?

How does Simon’s Model correspond to the Scientific Method and to the Systems Development Life Cycle

(SDLC)?

SIMON'S MODEL SCIENTIFIC APPROACH SDLC Intelligence Define Problem System Investigation

Design Develop Alternatives System Analysis Choice Select Solution / Design Solution System Design

Implementation Implement Solution Implementation Review Maintenance

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Management Information System and Decision Support System 5

Decision Support Systems Decision Support Systems (DSS) are a specific class of computerized information system that supports business and

organizational decision-making activities. A properly designed DSS is an interactive software-based system intended to

help decision makers compile useful information from raw data, documents, personal knowledge, and/or business

models to identify and solve problems and make decisions.

Typical information that a decision support application might gather and present would be: 1. Accessing all of your current information assets, including legacy and relational data sources, cubes, data

warehouses, and data marts

2. Comparative sales figures between one week and the next

3. Projected revenue figures based on new product sales assumptions

4. The consequences of different decision alternatives, given past experience in a context that is described

5. A DSS supports all phases of decision making and may include a knowledge component

6. A DSS can be used by a single user on a PC or can be Web-based for use by many people at several locations

typical information that a decision support application might gather and present would be.

Characteristics and capabilities of DSS 1. DSS provide support for decision makers mainly semi structured and unstructured situations by bringing

together human judgment and computer.

2. Support is provided for various managerial levels.

3. Support is provided to individuals as well as to groups.

4. DSS provide support to several interdependent and sequential decisions.

5. It supports all phases of the decision-making process.

6. DSS attempt to improve the effectiveness of decision making.

7. Decision maker has complete control over all steps of the decision making process in solving a problem .

8. A DSS usually utilizes models for analyzing decision-making situations.

Types of Decision Support Systems (DSS) - There are a number of Decision Support Systems. These can be

categorized into five types:

1. Communication-driven DSS - Most communications-driven DSSs are targeted at internal teams, including

partners. Its purpose are to help conduct a meeting, or for users to collaborate. The most common technology

used to deploy the DSS is a web or client server. Examples: chats and instant messaging software’s, online

collaboration and net-meeting systems.

2. Data-driven DSS - Most data-driven DSSs are targeted at managers, staff and also product/service suppliers. It

is used to query a database or data warehouse to seek specific answers for specific purposes. It is deployed via a

main frame system, client/server link, or via the web. Examples: computer-based databases that have a query

system to check (including the incorporation of data to add value to existing databases.

3. Document-driven DSS - Document-driven DSSs are more common, targeted at a broad base of user groups.

The purpose of such a DSS is to search web pages and find documents on a specific set of keywords or search

terms. The usual technologies used to set up such DSSs are via the web or a client/server system.

4. Knowledge-driven DSS: Knowledge-driven DSSs or 'knowledgebase' are they are known, are a catch-all

category covering a broad range of systems covering users within the organization setting it up, but may also

include others interacting with the organization - for example, consumers of a business. It is essentially used to

provide management advice or to choose products/services. The typical deployment technology used to set up

such systems could be silent/server systems, the web, or software running on stand-alone PCs.

5. Model-driven DSS - Model-driven DSSs are complex systems that help analyze decisions or choose between

different options. These are used by managers and staff members of a business, or people who interact with

the organization, for a number of purposes depending on how the model is set up - scheduling, decision

analyses etc. These DSSs can be deployed via software/hardware in stand-alone PCs, client/server systems, or

the web.

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Management Information System and Decision Support System

Components of Decision Support SystemsDecision support systems vary greatly in application and complexity, but they all share specific features.

Typical Decision support system has four components:

management and user interface management.

1. Data Management Component

maintaining the information that you want your Decision Support System to use. The data management

component, therefore, consists of both the Decision Support System information and the

System database management system. The information you use in your Decision Support System comes from

one or more of three sources:

� Organizational information

organization for your Decision Support System. What you use, of course, depends on what you need

and whether it is available. You can design your Decision Support System to access this information

directly from your company’s database and data warehouse. However, specifi

copied to the Decision Support System database to save time in searching through the organization’s

database and data warehouses.

� External information

branches of federal government, Dow Jones, Compustat data, and the internet, to mention just a few,

can provide additional information for the use with a Decision Support System.

� Personal information

information into your Decision Support System. You can design your Decision Support System so that

you enter this personal information only as needed, or you can keep the information in a personal

database that is accessible by the Decision Support

2. Model Management Component

� The model management component consists of both the Decision Support System models and

the Decision Support System model management system.

event, fact, or situation. As it is not a

build models and use them for experimentation. Models can take various forms.

� Businesses use models to represent variables and their relationships

use a statistical model

billboard advertizing are equally effective in increasing sales.

� Decision Support Systems help in various decision

allow you to analyze informati

System depend on the decision you are making and, consequently, the kind of analysis you require.

For example, you would use what

Management Information System and Decision Support System

Components of Decision Support Systems Decision support systems vary greatly in application and complexity, but they all share specific features.

Typical Decision support system has four components: data management, model management, knowledge

management and user interface management.

Data Management Component - The data management component performs the function of storing and

maintaining the information that you want your Decision Support System to use. The data management

component, therefore, consists of both the Decision Support System information and the

System database management system. The information you use in your Decision Support System comes from

Organizational information - you may want to use virtually any information available in the

r your Decision Support System. What you use, of course, depends on what you need

and whether it is available. You can design your Decision Support System to access this information

directly from your company’s database and data warehouse. However, specifi

copied to the Decision Support System database to save time in searching through the organization’s

database and data warehouses.

External information - some decisions require input from external sources of information. Various

hes of federal government, Dow Jones, Compustat data, and the internet, to mention just a few,

can provide additional information for the use with a Decision Support System.

Personal information - you can incorporate your own insights and experience your p

information into your Decision Support System. You can design your Decision Support System so that

you enter this personal information only as needed, or you can keep the information in a personal

database that is accessible by the Decision Support System.

Model Management Component –

The model management component consists of both the Decision Support System models and

the Decision Support System model management system. A model is a representation of some

event, fact, or situation. As it is not always practical, or wise, to experiment with reality, people

build models and use them for experimentation. Models can take various forms.

Businesses use models to represent variables and their relationships

use a statistical model called analysis of variance to determine whether newspaper, TV, and

billboard advertizing are equally effective in increasing sales.

Decision Support Systems help in various decision-making situations

allow you to analyze information in many different ways. The models you use in a Decision Support

System depend on the decision you are making and, consequently, the kind of analysis you require.

For example, you would use what-if analysis to see what effect the change of one or more v

Management Information System and Decision Support System 6

Decision support systems vary greatly in application and complexity, but they all share specific features.

data management, model management, knowledge

The data management component performs the function of storing and

maintaining the information that you want your Decision Support System to use. The data management

component, therefore, consists of both the Decision Support System information and the Decision Support

System database management system. The information you use in your Decision Support System comes from

you may want to use virtually any information available in the

r your Decision Support System. What you use, of course, depends on what you need

and whether it is available. You can design your Decision Support System to access this information

directly from your company’s database and data warehouse. However, specific information is often

copied to the Decision Support System database to save time in searching through the organization’s

some decisions require input from external sources of information. Various

hes of federal government, Dow Jones, Compustat data, and the internet, to mention just a few,

can provide additional information for the use with a Decision Support System.

you can incorporate your own insights and experience your personal

information into your Decision Support System. You can design your Decision Support System so that

you enter this personal information only as needed, or you can keep the information in a personal

The model management component consists of both the Decision Support System models and

A model is a representation of some

lways practical, or wise, to experiment with reality, people

build models and use them for experimentation. Models can take various forms.

Businesses use models to represent variables and their relationships. For example, you would

called analysis of variance to determine whether newspaper, TV, and

making situations by utilizing models that

on in many different ways. The models you use in a Decision Support

System depend on the decision you are making and, consequently, the kind of analysis you require.

if analysis to see what effect the change of one or more variables

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Management Information System and Decision Support System 7

will have on other variables, or optimization to find the most profitable solution given operating

restrictions and limited resources. Spreadsheet software such as excel can be used as a Decision

Support System for what-if analysis.

� The model management system stores and maintains the Decision Support System’s models.

Its function of managing models is similar to that of a database management system. The model

management component cannot select the best model for you to use for a particular problem that

requires your expertise but it can help you create and manipulate models quickly and easily.

3. User Interface Management Component - The user interface management component allows you to

communicate with the Decision Support System. It consists of the user interface management system. This is

the component that allows you to combine your know-how with the storage and processing capabilities of the

computer. The user interface is the part of the system you see through it when enter information, commands,

and models. This is the only component of the system with which you have direct contract. If you have a

Decision Support System with a poorly designed user interface, if it is too rigid or too cumbersome to use, you

simply won’t use it no matter what its capabilities. The best user interface uses your terminology and methods

and is flexible, consistent, simple, and adaptable.

4. Knowledge Management Component - The knowledge management component, like that in an expert

system, provides information about the relationship among data that is too complex for a database to

represent. It consists of rules that can constrain possible solution as well as alternative solutions and methods

for evaluating them.

Systems development life cycle (SDLC) The systems development life cycle (SDLC), or software development process, or Software Development Life Cycle

in systems engineering, information systems and software engineering, is a process of creating or altering

information systems, and the models and methodologies that people use to develop these systems. In software

engineering, the SDLC concept underpins many kinds of software development methodologies. These

methodologies form the framework for planning and controlling the creation of an information system.

What is systems development life cycle (SDLC)? The systems development life cycle (SDLC) is a conceptual model used in project management that describes the

stages involved in an information system development project, from an initial feasibility study through

maintenance of the completed application. Various SDLC methodologies have been developed to guide the

processes involved, including the waterfall model (which was the original SDLC method); rapid application

development (RAD); joint application development (JAD); the fountain model; the spiral model; build and fix; and

synchronize-and-stabilize. Frequently, several models are combined into some sort of hybrid methodology.

Documentation is crucial regardless of the type of model chosen or devised for any application, and is usually done

in parallel with the development process. Some methods work better for specific types of projects, but in the final

analysis, the most important factor for the success of a project may be how closely the particular plan was followed.

In general, an SDLC methodology follows the following steps:

1. The existing system is evaluated. Deficiencies are identified. This can be done by interviewing users of the

system and consulting with support personnel.

2. The new system requirements are defined. In particular, the deficiencies in the existing system must be

addressed with specific proposals for improvement.

3. The proposed system is designed. Plans are laid out concerning the physical construction, hardware,

operating systems, programming, communications, and security issues.

4. The new system is developed. The new components and programs must be obtained and installed. Users of

the system must be trained in its use, and all aspects of performance must be tested. If necessary,

adjustments must be made at this stage.

5. The system is put into use. This can be done in various ways. The new system can phased in, according to

application or location, and the old system gradually replaced. In some cases, it may be more cost-effective

to shut down the old system and implement the new system all at once.

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6. Once the new system is up and running for a while, it should be exhaustively evaluated. Maintenance must

be kept up rigorously at all times. Users of the system should be kept up-to-date concerning the latest

modifications and procedures.

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Database Management System

What is database? A database is a system intended to organize, store, and retrieve large amounts of data easily. It consists of an organized

collection of data for one or more uses, typically in digital form. One way of classifying databases involves the type of

their contents, for example: bibliographic, document-text, statistical. Digital databases are managed using database

management systems, which store database contents, allowing data creation and maintenance, and search and other

access.

Database Management System A DBMS is a complex set of software programs that controls the organization, storage, management, and

retrieval of data in a database. DBMS are categorized according to their data structures or types, sometime

DBMS is also known as Data base Manager. It is a set of prewritten programs that are used to store, update

and retrieve a Database a DBMS includes: A modeling language to define the schema of each database hosted in the

DBMS, according to the DBMS data model.

The functions of a current generation DBMS may be summarized as follows: 1. Stores the definitions of data and their relationships (metadata) in a data dictionary; any changes made are

automatically recorded in the data dictionary.

2. Creates the complex structures required for data storage.

3. Transforms entered data to conform to the data structures in item 2.

4. Creates a security system and enforces security within that system.

5. Creates complex structures that allow multiple user access to the data.

6. Performs backup and data recovery procedures to ensure data safety.

7. Promotes and enforces integrity rules to eliminate data integrity problems.

8. Provides access to the data via utility programs and from programming languages interfaces.

9. Provides end-user access to data within a computer network environment.

REQUIREMENTS FOR A DBMS - The various software’s which handle the data in a database i.e. DBMS (like Oracle,

FoxPro, and SQL Server etc.) should meet the following requirements: -

1. Provide data definition facilities.

� Define Data Definition Language (DDL)

� Provide user accessible catalog (Data Dictionary)

2. Provide facilities for storing, retrieving and updating data.

� Define Data Manipulation Language (DML)

3. Support Multiple View of Data

� End User or application should see only the need data and information required.

4. Provides facilities for specifying Integrity constraints.

� Primary Key Constraints

� Foreign Key Constraints

� More General Constraints

5. Provide facilities for controlling access to data.

� Prevent unauthorized access and update.

6. Allow simultaneous access and update by multiple users.

� Provide concurrency control mechanism.

7. Support Transactions.

� A sequence of operations to be performed as a whole.

� All operations are performed or none.

8. Provide facilities for database recovery.

� Bring database back to consistent state after a failure such as disk failure, faulty program etc.

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Management Information System and Decision Support System 10

9. Provide facilities for database maintenance.

� Maintenance operations: unload, reload, mass Insertion and deletion, validation etc.

STRUCTURE OF DBMS - DBMS (Database Management System) acts as an interface between the user and the

database. The user requests the DBMS to perform various operations (insert, delete, update and retrieval) on the

database. The components of DBMS perform these requested operations on the database and provide necessary data

to the users. The various components of DBMS are shown below: -

1. DDL Compiler - Data Description Language compiler processes schema definitions specified in the DDL. It

includes metadata information such as the name of the files, data items, storage details of each file, mapping

information and constraints etc.

2. DML Compiler and Query optimizer - The DML commands such as insert, update, delete, retrieve from the

application program are sent to the DML compiler for compilation into object code for database access. The

object code is then optimized in the best way to execute a query by the query optimizer and then send to the

data manager.

3. Data Manager - The Data Manager is the central software component of the DBMS also knows as Database

Control System.

� The Main Functions Of Data Manager Are: –

� Convert operations in user's Queries coming from the application programs or combination of DML

Compiler and Query optimizer which is known as Query Processor from user's logical view to physical file

system.

� Controls DBMS information access that is stored on disk.

� It also controls handling buffers in main memory.

� It also enforces constraints to maintain consistency and integrity of the data.

� It also synchronizes the simultaneous operations performed by the concurrent users.

� It also controls the backup and recovery operations.

4. Data Dictionary - Data Dictionary is a repository of description of data in the database. It contains information

about

� Data - names of the tables, names of attributes of each table, length of attributes, and number of rows in

each table.

� Relationships between database transactions and data items referenced by them which is useful in

determining which transactions are affected when certain data definitions are changed.

� Constraints on data i.e. range of values permitted.

� Detailed information on physical database design such as storage structure, access paths, files and record

sizes.

� Access Authorization - is the Description of database users their responsibilities and their access rights.

� Usage statistics such as frequency of query and transactions.

Data dictionary is used to actually control the data integrity, database operation and accuracy. It may be used

as an important part of the DBMS.

� Importance of Data Dictionary - Data Dictionary is necessary in the databases due to following reasons:

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� It improves the control of DBA over the information system and user's understanding of use of the system.

� It helps in document ting the database design process by storing documentation of the result of every

design phase and design decisions.

� It helps in searching the views on the database definitions of those views.

� It provides great assistance in producing a report of which data elements (i.e. data values) are used in all

the programs.

� It promotes data independence i.e. by addition or modifications of structures in the database application

program are not affected.

5. Data Files - It contains the data portion of the database.

6. Compiled DML - The DML complier converts the high level Queries into low level file access commands known

as compiled DML.

7. End Users - They are already discussed in previous section.

The advantages of DBMS 1. It represents complex relationships among different data items.

2. Keeps a tight control on data redundancy.

3. Enforces user defined rules to ensure the integrity of data in a table form.

4. Maintains data dictionary for the storage of information pertaining to data fields and data manipulation.

5. Ensures that data can be shared across all applications.

6. Enforces data access authorization.

7. Has an automatic intelligent backup and recovery procedure of data.

8. Have different interfaces through which users can manipulate data.

Types of DBMS: There are four structural types of database management systems: hierarchical, network, relational,

and object-oriented.

1. Hierarchical Databases- Hierarchical Databases (DBMS), commonly used on mainframe computers, have been

around for a long time. It is one of the oldest methods of organizing and storing data, and it is still used by some

organizations for making travel reservations. A hierarchical database is organized in pyramid fashion, like the

branches of a tree extending downwards. Related fields or records are grouped together so that there are

higher-level records and lower-level records, just like the parents in a family tree sit above the subordinated

children. Based on this analogy, the parent record at the top of the pyramid is called the root record. A child

record always has only one parent record to which it is linked, just like in a normal family tree. In contrast, a

parent record may have more than one child record linked to it. Hierarchical databases work by moving from

the top down. A record search is conducted by starting at the top of the pyramid and working down through the

tree from parent to child until the appropriate child record is found. Furthermore, each child can also be a

parent with children underneath it. The advantage of hierarchical databases is that they can be accessed and

updated rapidly because the tree-like structure and the relationships between records are defined in advance.

However, this feature is a two-edged sword. The disadvantage of this type of database structure is that each

child in the tree may have only one parent, and relationships or linkages between children are not permitted,

even if they make sense from a logical standpoint. Hierarchical databases are so rigid in their design that adding

a new field or record requires that the entire database be redefined.

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2. Network Databases - Network databases are similar to hierarchical databases by also having a hierarchical

structure. There are a few key differences, however. Instead of looking like an upside-down tree, a network

database looks more like a cobweb or interconnected network of records. In network databases, children are

called members and parents are called owners. The most important difference is that each child or member can

have more than one parent (or owner).Like hierarchical databases, network databases are principally used on

mainframe computers. Since more connections can be made between different types of data, network

databases are considered more flexible. However, two limitations must be considered when using this kind of

database. Similar to hierarchical databases, network databases must be defined in advance. There is also a limit

to the number of connections that can be made between records.

3. Relational Databases - In relational databases, the relationship between data files is relational, not

hierarchical. Hierarchical and network databases require the user to pass down through a hierarchy in order to

access needed data. Relational databases connect data in different files by using common data elements or a

key field. Data in relational databases is stored in different tables, each having a key field that uniquely

identifies each row. Relational databases are more flexible than either the hierarchical or network database

structures. In relational databases, tables or files filled with data are called relations, a tipple designates a row

or record, and columns are referred to as attributes or fields. Relational databases work on the principle that

each table has a key field that uniquely identifies each row, and that these key fields can be used to connect one

table of data to another. Thus, one table might have a row consisting of a customer account number as the key

field along with address and telephone number. The customer account number in this table could be linked to

another table of data that also includes customer account number (a key field), but in this case, contains

information about product returns, including an item number (another key field). This key field can be linked to

another table that contains item numbers and other product information such as production location, color,

quality control person, and other data. Therefore, using this database, customer information can be linked to

specific product information. The relational database has become quite popular for two major reasons. First,

relational databases can be used with little or no training. Second, database entries can be modified without

redefining the entire structure. The downside of using a relational database is that searching for data can take

more time than if other methods are used.

4. Object-oriented Databases (OODBMS) - Able to handle many new data types, including graphics,

photographs, audio, and video, object-oriented databases represent a significant advance over their other

database cousins. Hierarchical and network databases are all designed to handle structured data; that is, data

that fits nicely into fields, rows, and columns. They are useful for handling small snippets of information such as

names, addresses, zip codes, product numbers, and any kind of statistic or number you can think of. On the

other hand, an object-oriented database can be used to store data from a variety of media sources, such as

photographs and text, and produce work, as output, in a multimedia format. Object-oriented databases use

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Management Information System and Decision Support System 13

small, reusable chunks of software called objects. The objects themselves are stored in the object-oriented

database. Each object consists of two elements: 1) a piece of data (e.g., sound, video, text, or graphics), and 2)

the instructions, or software programs called methods, for what to do with the data. Part two of this definition

requires a little more explanation. The instructions contained within the object are used to do something with

the data in the object. For example, test scores would be within the object as would the instructions for

calculating average test score. Object-oriented databases have two disadvantages. First, they are more costly

to develop. Second, most organizations are reluctant to abandon or convert from those databases that they

have already invested money in developing and implementing. However, the benefits to object-oriented

databases are compelling. The ability to mix and match reusable objects provides incredible multimedia

capability. Healthcare organizations, for example, can store, track, and recall CAT scans, X-rays,

electrocardiograms and many other forms of crucial data.