Mba it unit 3 ppt

PRESENTED BY……
INFORMATION SYSTEM
VIVEK
PLANNING AND
SARITHA
DEVELOPMENT USHA
RAVALI
TEJASWI
SMRUTHI
RAMYA

SYSTEM DEVLOPMENT
LIFE CYCLE(SDLC)
(1) Systems Investigation An eight-stage systems
(2) Systems Analysis development life cycle
(3) Systems Design (SDLC)
(4) Programming

(5) Testing

(6) Implementation
(7) Operation

(8) Maintenance

Go Back to a previous Stage or Stop

SDLC (continued …)
 Systems Investigation (Step 1)
 Feasibility Study determines the probability
of success of proposed system’s
development project and assesses the
project’s
technical feasibility : determines if the hardware,
software, and communication components can be
developed or acquired to solve the business problem
 economic feasibility : determines if the project is an
acceptable financial risk and if the organization can
afford the expense and time needed to complete the
project
 behavioral feasibility : addresses the human issues of
the project

 Systems Analysis (Step 2)
 the examination of the business
problem that the organization plans to
solve with information systems
 produces the following information
strengths and weaknesses of the
existing system
functions that the new systems must
have to solve the business problem
user information requirements for the
new systems

Systems Design (Step 3)
describes how the system will accomplish the
task
technical design
system outputs, inputs, and user interfaces
hardware, software, databases, telecommunications,
personnel, and procedures
how these components are integrated
local systems design : what the system will do
Physical systems design : how the system will
perform its functions

SDLC
Programming (Step 4)
the translation of the design specifications
into computer code
structured programming techniques :
improve the logical flow of the program by
decomposing the computer code into
modules, which are sections of code
sequence structure
decision structure
loop structure

SDLC

 Testing (Step 5)
 checks to see if the computer code
will produce the expected and
desired results under certain
conditions
 syntax errors : misspelled word or a
misplaced comma
 logic errors : permit the program to
run, but result in incorrect output

SDLC
Implementation (Step 6)
the process of converting from the old system to the new
system
four major conversion strategies
parallel conversion : the old and new systems operate
simultaneously for a period of time
direct conversion : the old system is cut off and the
new systems is turned on at a certain point in time
pilot conversion : introduces the new system in one
part of the organization
phased conversion : introduces components of the
new systems in stages

SDLC
 Operation (Step 7)
 the new systems will operate for a
period of time, until it no longer meets
its objectives
 Maintenance (Step 8)
 debugging the program
 updating the system to accommodate
changes in business conditions
 add new functionality to the system

INFORMATION SYSTEM
PLANNING
 I/S starts with gaining a holistic
perspective on what the firm aims to
achieve.
 System development is the entire set of
activities needed to construct an I/S to a
business problem/opportunity.
 I/S is the key component which begins
with the strategic plan of the
organization.

STRATEGIC PLANNING OF
THE ORGANIZATION

The I/S Strategic plan…
The I/S strategic plan is a set of long range
goals.
The I/s strategic plan must meet 3 objectives.
 It must be aligned with the organizations
strategic plan.
 It must be provide for an it architecture that
enables users,applications, and databases to
be seamlessly networked and integrated
 By I/S we can complete project in time, within
budget, and have required funcionality

The I/S Operation plan
I/S strategic plan leads to I/S operational plan.
A typical IS operational plan contains the
following elements.
 MISSION
 I/S ENVIRONMENT
 OBJECTIVE OF THE I/SFUNCTION.
 CONSTRAINT OF THE I/S FUNCTION.
 LONG TERM SYSTEM NEEDS.
 SHORT-RANGE PLAN.

Alternative methods to the
Systems development
 Two main problems with the SDLC
 Time consuming
 User requirements change over time
 Expensive

Different Methods
 Prototyping
 Joint Application Design
 Rapid application development (RAD)
 ICASE Tools
 Object Oriented Development

Prototyping
 Prototyping is an
information-
gathering technique
 Prototypes are
useful in seeking
user reactions,
suggestions,
innovations, and
revision plans

Prototype Advantages
 Potential for changing the system early
in its development
 Opportunity to stop development on an
unworkable system
 Possibility of developing a system that
closely addresses users' needs and
expectations

Prototype Disadvantages
 Managing the prototyping process is
difficult because of its iterative nature
and it is time consuming
 It can largely replace analysis and
design stages.

Joint Application Design
 It is a group-based method for
collecting user requirements and
creating system designs.

JAD- Advantages
 The group process involves more users
in the development process.
 Easier implementation of the new
system.
 Low training costs.

JAD- Disadvantages
 Difficult to get all users to JAD meeting

 It has all problems caused by any group
process.

Rapid Application
Development (RAD)
 Rapid application development is a
systems development that includes a
method of development as well as
software tools to rapidly produce a high
quality system.

RAD Phases
 There are three broad phases to RAD:
 Requirements planning
 RAD design workshop
 Implementation

Requirements Planning Phase
 Users and analysts meet to identify
objectives of the application or system
 Oriented toward solving business
problems

RAD Design Workshop
 Design and refine phase
 Use group decision support systems to
help users agree on designs
 Programmers and analysts can build and
show visual representations of the designs
and workflow to users
 Users respond to actual working
prototypes
 Analysts refine designed modules based
on user responses

Implementation Phase
 As the systems are built and refined,
the new systems or partial systems are
tested and introduced to the
organization
 When creating new systems, there is no
need to run old systems in parallel

RAD - Advantages
 Active involvement of users in the
development process.
 Reduces development cost
 Create applications that are easier to
maintain and modify

Using RAD Within the SDLC
 RAD is very powerful when used within
the SDLC
 It can be used as a tool to update,
improve, or innovate selected portions
of the system

Disadvantages of RAD
 It produces system with limited
functionality and flexibility for change
 Therefore system may not be able to
respond to changing business
conditions
 Produce system that are not of high
quality

ICASE TOOLs
 Computer-aided software engineering tools
automate many of the tasks in SDLC.
 The tools used to automate the early stages
of SDLC is Upper case tools.
 The tools used automate the later stages in
the SDLC are lower case tools
 CASE tools that provides link between upper
and lower case tools are called Integrated
CASE tools.

ICASE Advantages
 Produce systems with a longer effective
operational life
 Flexible and adaptable to changing
business conditions.
 Have excellent documentation

ICASE Disadvantages
 Produce systems which are more
expensive to built and maintain.
 These are difficult to use with existing
system.

Why Object Oriented
Development
 SDLC development approaches provide
specific step-by-step instructions in the
form of computer programs
 These programs usually result in
system that performs the original task
but may not be suited for handling other
tasks.

Object Oriented Development
 An object oriented system begins not
with the task to be perform, but with
aspects of the real world that must be
modeled to perform the task.

Advantages of OO system
 It produces the system that are easy to
built and maintain.
 Once an object is designed and tested
it can be reused in other systems.
 System developed with OO approach
are more flexible.

Object-oriented analysis and
desing(OOA&D)
 In this approach system developers
identify the objects
OBJECTS:
 It is a fundamental elements in OOAD
 It represents tangible real world entities
Ex: customer, bank account, student.
 Objects have properties and operations
that can be performed on their
properties

Advatages of OOAD
 It defines all relevant objects their
properties(data values) and their
operations(behaviours)
 Here objects have relationship to meet
the objective of new system
 Existing object can be used for other
application saving the time spent on
coding

DATAFLOW ANALYSIS
 Data flow analysis is known as structured
analysis
 It performs the following activities
 Defining inputs, outputs and process that are
related to system
 Developing a logical model of proposed
system
 partitioning the system into different modules
 Defining the process or transformations
performed on individual modules
 Defining relationship b/w modules

ADVANTAGES
 It helps analyst in detecting the errors at
early stages
 There by reducing time and cost
incurred in detecting errors at later
stages

Tools for performing
Structured system analysis
 Dataflow diagrams
 Illustrates logical view rather than physical
view of business process
 Logical view can be represented using logical
dataflow diagrams
Symbols used are ROUND RECTANGLE,
SQUARE, ARROW.
 Data dictionary
 These specify components present in
structure along with structure of files displayed
in data flow diagrams

System development outside
the IS department
Four methods for developing system
outside the information department are:
 END-USER DEVELOPMENT
 EXTERNAL ACQUISITION OF
SOFTWARE
 APPLICATION SERVICE PROVIDER
 OUTSOURCING

END-USER DEVELOPMENT
 End user computing
 Fulfilling the information requirements of
all departments.
 Ability of supporting adhoc query and
reporting languages.

ADVANTAGES:
 Level of user satisfaction incresed.

DISADVANTAGES:
Fails to address the backlog problem.
No procedures for recovery process.
Cannot perform data validation.
Cannot detect errors.

External Acquisition of
Software
 Method of developing or purchasing
software from external vendor
 Make-or-buy decision
 Quality of software increased
Some of the Factors to be followed
 Cost and financial factors
 Graphical presentation
 Security
 Data management capabilities

ADVANTAGES:
1)Reduces initial cost of existing software
2)Satisfies all business requirements of an
organization

DISADVATAGES:
Requires large number of requirements
Requires huge amount of cost
Very expensive to modify

Application Service
Provider(ASP)

 Method of providing applications only to
subscribed organization
 Applications are hosted on asp’s data
center and users can access them or
carried out through “virtual private n/w”
 These are not sold or licensed

ADVANTAGES: DISADVANTAGES:

 Minimizes internal  Fails to provide
IT cost customized solutions
 Provides to all clients
information about  Not flexible to
available products changes
 Increase the  Cannot be integrated
performance level

OUTSOURCING
 It is a practice where a
company purchases a
product from another
company
 Outsources the work to
external vendor
 External vendor creates the
software and he is paid for it
EX: ASP

ADVANTAGES AND
DISADVANTAGES
 Outsourcing can reduce the cost
 This can built the system even when
internal resources are unavailable
 Organization loses control over its
information system function
 It results in high cost

DATABASE
 A database is a structured collection
of data
 Databases are designed to offer an
organized mechanism for storing,
managing and retrieving information.

File Oriented Approach
 In early days,day was stored in files.
 For an application,multiple files are
required to be created.
 Each file stores and maintains its own
related data.

Limitations of File oriented
approach
 Data redundancy and inconsistency: Different files
may have different formats and the programs may be
written in different programming languages as they are
developed by different programmers. Moreover, the same
information may be duplicated in several places (files).
 For example, the address and telephone number of a
particular customer may appear in a file that consists of
saving-account records and in a file that consists of
checking-account records. This redundancy leads to
higher storage and access cost. It may lead to data
inconsistency; that is. The various copies of the same
data may no longer agree.

Limitations of File oriented
approach
 Difficulty in accessing data: Suppose we need
to access information about all the customers of a
particular scheme. During the initial stages of
development of the system this kind of query might
not have been known, no application program would
be on hand to meet it. Say we have the application
program that generates list of all the customers along
with the scheme names. Thus we will have to run the
latter program and sort the customers of particular
scheme manually, or for each query we will have to
write a new application program. Clearly we can see
that accessing data is not easy in these cases.

Problems with file oriented
approach
 Data isolation: Since data is scattered in various files, which might
be in different formats thus, it is difficult to write a new application to
retrieve appropriate data.

 Integrity Problems: The data values stored in the database must
satisfy certain types of consistency constraints. For example, the
balance of a bank account may never fall below a prescribed amount
(say, Rs. 500). Developers enforce these constraints in the system
through hard coding these conditions. When new constraints are
added, it is difficult to change the program to enforce them.

 Security problems: Every person should not be allowed to access
the database for security purposes. Since application programs are
added to the system in an ad-hoc manner, it is difficult to ensure such
security constraints.

Advantages of the Database
Approach
 Data Independence :
The data is held in such a way that changes to the structure of
the database do not effect any of the programs used to access
the data.
 Consistency of Data :
Each item of data is held only once therefore no danger of item
being updated on one system and not on another.
 Data Redundancy is minimised :
In a non-database system, the same information may be held
on several files. This wastes space and makes updating more
time-consuming. A database system minimizes these effects.
 Integrity of Data :
The DBMS provides users with the ability to specify constraints
on data such as making a field entry essential or using a
validation routine.

Advantages of the Database
Approach
 Greater Security of Data :
The DBMS can ensure only authorized users are allowed access to
the data.
 Centralized Control of Data :
The Database Administrator will control who has access to what
and will structure the database with the needs of the
 More Information Available to Users :
Users have access to a wider range of data that was previously
held in seperate departments and sometimes on incompatible
systems.
 Increased Productivity :
The DBMS provides an easy to use query language that allows
users to get immediate response from their queries rather than
having to use a specialist "programmer" to write queries for them
whole department in mind

Disadvantages of the
Database Approach
 Larger Size :
More disk space is required and probably a larger
and more p owerful computer
 Greater Complexity :
For optimum use the database must be very
carefully designed. If not done well, the new
system may fail to satisfy anyone.
 Greater Impact of System Failure :
"All eggs in one basket.“
 More Complex Recovery Procedures :
If a system failure occurs it is vital that no data is
lost

Database
A database is any organized
collection of data.

An UNIVERSITY example
 A UNIVERSITY database for maintaining information
concerning students, courses, and grades in a
university environment

 We have:
STUDENT file stores data on each student
COURSE file stores data on each course
SECTION file stores data on each section of each
course
GRADE_REPORT file stores the grades that students
receive

Types of Data models
1.Object based logical models
The entity-relationship models
The Object-oriented model
The semantic data model
The functional data model

2.Record based logical models
Relational model
Network model
Hierarchical model

3.Physical data model
M.G. Erechtchoukova 61

Object based logical
models

 Used in describing data at logical level
and view level
 Logical level is to make a decision
regarding what data are to be stored in
the database and what relationships
must exist among those data.
 View level describes only part of the
entire database that is to viewed by the
database user.

Entity-relationship models (ERM)

Is based on a collection of basic objects called
entities, and the relationship among these objects.

In this step, the database designer creates an entity-
relationship (E-R) diagram to show the entities for
which information needs to be stored and the
relationship between those entities.

Figure shows a very simple E-R diagram with three entity sets,
their attributes and the relationship between the entity sets.

Fig: Entities, attributes and relationships in an E-R diagram

Object-Oriented Databases (OODB)

 Is based on a collection of objects

 Object contains values stored in instances
variables, methods (bodies of code) that
operates on the object

 Object that contains the same types of values
and same methods are grouped together into
classes.

Semantic Data model

 It makes easier for a user to give
starting description of data in an
enterprise
 Contain a wide variety of relations that
helps to describe a real application
scenario

66

Functional Data model

 Is easier to define functions and call
them wherever necessary to process
data

67

Record based logical models

 Named because the data is kept in the
form of records (documents) of several
types

 Each record has fixed number of fields
and each field is of fixed length

68

Relational database model
In the relational model, data is organized in two-dimensional
tables called relations. The tables or relations are, however,
related to each other, as we will see shortly .

Figure: An example of the relational model representing a university

Hierarchical database model
In the hierarchical model, data is organized as an inverted
tree. Each entity has only one parent but can have several
children. At the top of the hierarchy, there is one entity,
which is called the root.

Figure: An example of the hierarchical model representing a university

Network database model
In the network model, the entities are organized in a graph,
in which some entities can be accessed through several paths
(Figure 14.4).

Figure 14.4 An example of the network model representing a university
14.71

OTHER DATABASE MODELS

 Distributed data bases
 Object oriented data base
 Active data base
 Parallel data base
 Multimedia data base
 Web data base

Distributed
Database - A logically interrelated
collection of shared data (and a
description of this data), physically
distributed over a computer network .
DBMS - Software system that permits
the management of the distributed
database and makes the distribution
transparent to users.

Advantages

 Increase reliability and availability.
 Easier expansion.
 Improved performance
 Reliable transactions
 Economic

Disadvantages

 Complexity
 Security
 Economics
 Inexperience
 Difficult to maintain integrity

NORMALIZATION
 Process of efficiently organizing data in
database
 Eliminating data redundancy
 Reducing design flaws
How to achieve
 Dividing database into two or more tables
 Defining relationship between them

Why normalization
 Normalization objective is to isolate
data so that additions, deletions and
modifications made in one table is
applicable to rest of tables in database

NORMAL FORMS
 Normal forms are applied to achieve
normalized data
 Normal forms are the conditions that a
table should fulfill

Different types of normal forms
 First normal form(1NF)
 Second normal form(2NF)
 Third normal form(3NF)
 Boyce-codd normal form(BCNF)
 Fourth normal form(4NF)
 Fifth normal form(5NF)

Different type of keys
 PRIMARY KEY
 COMPOSITE KEY
 CANDIDATE KEY
 SUPER KEY
 FOREIGN KEY

FIRST NORMAL FORM(1NF)
 Each attribute must be atomic
 No repeating columns within a row
 No multi-valued columns
 This disallows “attribute as collection of
tuples”
 Drawback
 Redundancy of data

Examples of 1NF
Employee (unnormalized)
Emp-no name Dept-no Dept-name skills
1 Kevin jacobs 201 R&D C
Perl
java
2 Barbara jones 224 IT Linux
mac
3 Jake rivera 201 R&D DB2
Oracle
JAVA

Employee (1NF)
emp_no name dept_no dept_name skills
1 Kevin Jacobs 201 R&D C
1 Kevin Jacobs 201 R&D Perl
1 Kevin Jacobs 201 R&D Java
2 Barbara Jones 224 IT Linux
2 Barbara Jones 224 IT Mac
3 Jake Rivera 201 R&D DB2
3 Jake Rivera 201 R&D Oracle
3 Jake Rivera 201 R&D Java

SECOND NORMAL
FORM(2NF)
 FUNCTIONAL DEPENDENCY:
 This can be defined as every non-key
attribute is dependent on the primary key
attribute
 PARTIAL FUCTIONAL DEPENDENCY
 If an attribute is not dependent on all of
the keys in the relation, we say that it has
partial dependency on the key.

Partial Functional
Dependence
Employee (1NF)

Skills is not functionally dependent on emp_no since it is not
unique to each emp_no.

SECOND NORMAL
FORM(2NF)
 Meet all the requirements of 1NF
 All partial dependencies must be
removed by dividing the table into small
tables and building relationships
between them

Example of 2NF
Employee (1NF)

Skills (2NF)
Employee (2NF) emp_no skills
1 C
emp_no name dept_no dept_name 1 Perl
1 Kevin Jacobs 201 R&D 1 Java
2 Barbara Jones 224 IT 2 Linux
3 Jake Rivera 201 R&D 2 Mac
3 DB2
3 Oracle
3 Java

Third normal form(3NF)
 Transitive dependencies
 A transitive functional dependency is when changing a
non-key column , might cause any of the other non-key
columns to change
Employee (2NF)
emp_no name dept_no dept_name
1 Kevin Jacobs 201 R&D
2 Barbara Jones 224 IT
3 Jake Rivera 201 R&D

Changing in Dept_no it also reflects on dept_name

Third normal form(3NF)
 Meet all the requirements of 2NF
 Remove all transitive dependencies
 Any transitive dependencies are moved
into a smaller (subset) table.

Examples of 3NF

Employee (2NF)
emp_no name dept_no dept_name
1 Kevin Jacobs 201 R&D
2 Barbara Jones 224 IT
3 Jake Rivera 201 R&D

Employee (3NF) Department (3NF)
emp_no name dept_no dept_no dept_name
1 Kevin Jacobs 201 201 R&D
2 Barbara Jones 224 224 IT
3 Jake Rivera 201

Boyce-codd Normal
Form(BCNF)
 BCNF is based on the concept of
a determinant(left hand attribute)
 A determinant is any attribute (simple or
composite) on which some other
attribute is fully functionally dependent.
 A relation is in BCNF if, and only if,
every determinant is a candidate key.

Examples of BCNF
Student (un normalized)
STUDENT MAJOR ADVISOR
1 chemistry P
2 Maths Q
3 Social R
4 English S
5 chemistry p

STUDENT ADVISOR
ADVISOR MAJOR
1 P
P chemistry
2 Q
Q Maths
3 R
R Social
4 S
S English
5 P

Fourth Normal Fourth
 Either of these conditions must hold true in
order to be fourth normal form
 There is no multivalued dependency in the relation
 There are multivalued dependency but the
attributes are dependent between themselves
 The relation must also be in BCNF
 Fourth normal form differs from BCNF only in
that it uses multivalued dependencies

Multivalued
Dependencies(MVD)
 Given a relation R, let x and y be
attributes of R. Then MVD denoted as
xy satisfied in relation R if
 t1(x)=t2(x)=t3(x)=t4(x)
 t1(y)=t3(y) and t2(y)=t4(x)
X Y Z tuples xy
a b1 c1 tuples-1
a b2 c2 tuples-2
a b1 c2 tuples-3
a b2 c1 tuples-4

Example of 4NF
B C A D tuples
b c1 a1 d1 tuples-1
b c2 a2 d2 tuples-2
b c1 a2 d2 tuples-3

MVD:BC
FD:ABCD
As the relation has both FDs and MVDs it is in 4NF

Fifth normal form(5NF)
 Any remaining anomalies are removed

Mba it unit 3 ppt

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