Management Information
System and Decision Support
System Semiester - 3
Kolhan University
Sandeep Ghatuary
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
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
Management Information System and Decision Support System 4
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
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.
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
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.
Management Information System and Decision Support System 8
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.
Management Information System and Decision Support System 9
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.
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:
Management Information System and Decision Support System 11
� 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.
Management Information System and Decision Support System 12
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
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.