information system planning and development
TRANSCRIPT
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INFORMATION SYSTEM
PLANNING ANDDEVELOPMENT
PRESENTED BY……
VIVEK
SARITHA
USHA
RAVALITEJASWI
SMRUTHI
RAMYA
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SYSTEM DEVLOPMENT LIFECYCLE(SDLC)
Go Back to a previous Stage or Stop
(1) Systems Investigation
(2) Systems Analysis
(3) Systems Design
(4) Programming
(5) Testing
(6) Implementation
(7) Operation
(8) Maintenance
An eight-stage systems
development life cycle
(SDLC)
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SDLC (continued …)
Systems Investigation (Step 1)Feasibility Study determines the probability
of success of proposed system’sdevelopment project and assesses theproject’s technical feasibility : determines if the hardware,
software, and communication components can bedeveloped or acquired to solve the business problem
economic feasibility : determines if the project is anacceptable financial risk and if the organization canafford the expense and time needed to complete theproject
behavioral feasibility : addresses the human issues of theproject
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SDLC (continued …)
Systems Analysis (Step 2) the examination of the business
problem that the organization plans tosolve with information systems
produces the following information
strengths and weaknesses of the
existing systemfunctions that the new systems must
have to solve the business problem
user information requirements for the
new systems
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SDLC(continued …)
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
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SDLC
Programming (Step 4) the translation of the design specifications
into computer code structured programming techniques :
improve the logical flow of the program bydecomposing the computer code intomodules, which are sections of code
sequence structure decision structure loop structure
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SDLC
Testing (Step 5)
checks to see if the computer codewill produce the expected anddesired results under certainconditions
syntax errors : misspelled word or amisplaced comma
logic errors : permit the program torun, but result in incorrect output
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SDLC Implementation (Step 6)
the process of converting from the old system to the newsystem
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
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SDLCOperation (Step 7)
the new systems will operate for a
period of time, until it no longer meetsits objectives
Maintenance (Step 8)
debugging the programupdating the system to accommodate
changes in business conditions
add new functionality to the system
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I/S starts with gaining a holisticperspective 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.
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STRATEGIC PLANNING OFTHE ORGANIZATION
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The I/S Strategic plan…
The I/S strategic plan is a set of long rangegoals.
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 thatenables users,applications, and databases tobe seamlessly networked and integrated
By I/S we can complete project in time,
within budget, and have required funcionality
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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.
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Alternative methods to theSystems development
Two main problems with the SDLC
Time consuming
User requirements change over time
Expensive
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Different Methods
Prototyping
Joint Application Design
Rapid application development (RAD)
ICASE Tools
Object Oriented Development
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Prototyping
Prototyping is aninformation-
gathering techniquePrototypes are
useful in seeking
user reactions,suggestions,innovations, and
revision plans
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Prototype Advantages
Potential for changing the system earlyin its development
Opportunity to stop development on anunworkable system
Possibility of developing a system that
closely addresses users' needs andexpectations
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Prototype Disadvantages
Managing the prototyping process isdifficult because of its iterative nature
and it is time consumingIt can largely replace analysis and
design stages.
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Joint Application Design
It is a group-based method forcollecting user requirements and
creating system designs.
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JAD- Advantages
The group process involves more usersin the development process.
Easier implementation of the newsystem.
Low training costs.
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JAD- Disadvantages
Difficult to get all users to JAD meeting
It has all problems caused by any groupprocess.
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Rapid Application Development(RAD)
Rapid application development is asystems development that includes a
method of development as well assoftware tools to rapidly produce a highquality system.
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RAD Phases
There are three broad phases to RAD:
Requirements planning
RAD design workshop
Implementation
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Requirements Planning Phase
Users and analysts meet to identifyobjectives of the application or system
Oriented toward solving businessproblems
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RAD Design Workshop
Design and refine phase
Use group decision support systems to
help users agree on designsProgrammers and analysts can build and
show visual representations of the designsand workflow to users
Users respond to actual working prototypes
Analysts refine designed modules based onuser responses
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Implementation Phase
As the systems are built and refined,the new systems or partial systems are
tested and introduced to theorganization
When creating new systems, there is no
need to run old systems in parallel
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RAD - Advantages
Active involvement of users in thedevelopment process.
Reduces development cost
Create applications that are easier tomaintain and modify
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Using RAD Within the SDLC
RAD is very powerful when used withinthe SDLC
It can be used as a tool to update,improve, or innovate selected portionsof the system
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Disadvantages of RAD
It produces system with limitedfunctionality and flexibility for change
Therefore system may not be able torespond to changing businessconditions
Produce system that are not of highquality
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ICASE TOOLs
Computer-aided software engineering toolsautomate many of the tasks in SDLC.
The tools used to automate the early stagesof SDLC is Upper case tools.
The tools used automate the later stages inthe SDLC are lower case tools
CASE tools that provides link between upperand lower case tools are called IntegratedCASE tools.
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ICASE Advantages
Produce systems with a longer effectiveoperational life
Flexible and adaptable to changingbusiness conditions.
Have excellent documentation
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ICASE Disadvantages
Produce systems which are moreexpensive to built and maintain.
These are difficult to use with existingsystem.
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Why Object OrientedDevelopment
SDLC development approaches providespecific step-by-step instructions in the
form of computer programsThese programs usually result in system
that performs the original task but may
not be suited for handling other tasks.
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Object Oriented Development
An object oriented system begins notwith the task to be perform, but with
aspects of the real world that must bemodeled to perform the task.
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Advantages of OO system
It produces the system that are easy tobuilt and maintain.
Once an object is designed and tested itcan be reused in other systems.
System developed with OO approach
are more flexible.
Obj i d l i d
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Object-oriented analysis anddesing(OOA&D)
In this approach system developersidentify 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 operationsthat can be performed on their
properties
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Advatages of OOAD
It defines all relevant objects theirproperties(data values) and their
operations(behaviours)Here objects have relationship to meet
the objective of new system
Existing object can be used for otherapplication saving the time spent oncoding
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DATAFLOW ANALYSIS
Data flow analysis is known as structuredanalysis
It performs the following activitiesDefining 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 transformationsperformed on individual modules
Definin relationshi b w modules
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ADVANTAGES
It helps analyst in detecting the errorsat early stages
There by reducing time and costincurred in detecting errors at laterstages
T l f f i
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Tools for performingStructured system analysis
Dataflow diagrams
Illustrates logical view rather than physical
view of business processLogical view can be represented using logical
dataflow diagrams
Symbols used are ROUND RECTANGLE,
SQUARE, ARROW. Data dictionary
These specify components present in structurealong with structure of files displayed in dataflow diagrams
S t d l t t id
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System development outsidethe IS department
Four methods for developing systemoutside the information department are:
END-USER DEVELOPMENT EXTERNAL ACQUISITION OF SOFTWARE
APPLICATION SERVICE PROVIDER
OUTSOURCING
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END-USER DEVELOPMENT
End user computing
Fulfilling the information requirements
of all departments.
Ability of supporting adhoc query andreporting languages.
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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.
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External Acquisition of Software
Method of developing or purchasingsoftware from external vendor
Make-or-buy decisionQuality of software increased
Some of the Factors to be followed
Cost and financial factors Graphical presentation
Security
Data management capabilities
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DISADVATAGES:
Requires large number of requirementsRequires huge amount of cost
Very expensive to modify
ADVANTAGES: 1)Reduces initial cost of existing software
2)Satisfies all business requirements of anorganization
A li ti S i
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Application ServiceProvider(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
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ADVANTAGES:
Minimizes internalIT cost
Providesinformation aboutavailable products
Increase theperformance level
DISADVANTAGES:
Fails to providecustomized
solutions to allclients
Not flexible to
changes Cannot be
integrated
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OUTSOURCING
It is a practice where acompany purchases a
product from anothercompany
Outsources the work to
external vendorExternal vendor creates the
software and he is paid for it
EX: ASP
ADVANTAGES AND
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ADVANTAGES ANDDISADVANTAGES
Outsourcing can reduce the cost
This can built the system even when
internal resources are unavailable
Organization loses control over itsinformation system function
It results in high cost
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DATABASE
A database is a structured collection of data
Databases are designed to offer anorganized mechanism for storing,managing and retrieving information.
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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 ownrelated data.
Limitations of File oriented
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Limitations of File orientedapproach
Data redundancy and inconsistency: Different filesmay have different formats and the programs may bewritten in different programming languages as they are
developed by different programmers. Moreover, the sameinformation may be duplicated in several places (files).
For example, the address and telephone number of aparticular customer may appear in a file that consistsof saving-account records and in a file that consists of
checking-account records. This redundancy leads tohigher storage and access cost. It may lead to datainconsistency; that is. The various copies of the samedata may no longer agree.
Limitations of File oriented
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Limitations of File orientedapproach
Difficulty in accessing data: Suppose we need toaccess information about all the customers of aparticular scheme. During the initial stages of
development of the system this kind of query mightnot have been known, no application program wouldbe on hand to meet it. Say we have the applicationprogram that generates list of all the customers along
with the scheme names. Thus we will have to run thelatter program and sort the customers of particularscheme manually, or for each query we will have towrite a new application program. Clearly we can seethat accessing data is not easy in these cases.
Problems with file oriented
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Problems with file orientedapproach
Data isolation: Since data is scattered in various files, which might bein different formats thus, it is difficult to write a new application toretrieve appropriate data.
Integrity Problems: The data values stored in the database mustsatisfy certain types of consistency constraints. For example, thebalance of a bank account may never fall below a prescribed amount(say, Rs. 500). Developers enforce these constraints in the systemthrough hard coding these conditions. When new constraints areadded, it is difficult to change the program to enforce them.
Security problems: Every person should not be allowed to access thedatabase for security purposes. Since application programs are addedto the system in an ad-hoc manner, it is difficult to ensure suchsecurity constraints.
Advantages of the Database
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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 itembeing updated on one system and not on another.
Data Redundancy is minimised :
In a non-database system, the same information may be held onseveral 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 avalidation routine.
Advantages of the Database
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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
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Disadvantages of the Database Approach
Larger Size :More disk space is required and probably a largerand more p owerful computer
Greater Complexity :For optimum use the database must be verycarefully designed. If not done well, the newsystem 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 islost
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Database
A database is any organized
collection of data.
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An UNIVERSITY example
A UNIVERSITY database for maintaining informationconcerning students, courses, and grades in auniversity environment
We have:STUDENT file stores data on each studentCOURSE file stores data on each courseSECTION file stores data on each section of each
courseGRADE_REPORT file stores the grades that students
receive
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Example of a simple database
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Types of Data models1.Object based logical models
The entity-relationship models
The Object-oriented model
The semantic data model
The functional data model
2.Record based logical modelsRelational model
Network model
Hierarchical model
3.Physical data model
M.G. Erechtchoukova 61
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Object based logical models
Used in describing data at logical leveland view level
Logical level is to make a decisionregarding what data are to be stored inthe 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.
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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 therelationship between those entities.
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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
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Is based on a collection of objects
Object contains values stored in instancesvariables, methods (bodies of code) thatoperates on the object
Object that contains the same types of valuesand same methods are grouped together intoclasses.
Object-Oriented Databases (OODB)
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Semantic Data model
It makes easier for a user to givestarting description of data in an
enterpriseContain a wide variety of relations that
helps to describe a real application
scenario
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Functional Data model
Is easier to define functions and callthem wherever necessary to process
data
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Record based logical models
Named because the data is kept in theform of records (documents) of several
types
Each record has fixed number of fields
and each field is of fixed length
68
Relational database model
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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
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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
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14.71
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
OTHER DATABASE MODELS
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OTHER DATABASE MODELS
Distributed data bases
Object oriented data base
Active data base
Parallel data base
Multimedia data base
Web data base
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Distributed Databases
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Distributed
Database - A logically interrelated
collection of shared data (and a
description of this data), physicallydistributed over a computer network .
DBMS - Software system that permits
the management of the distributeddatabase and makes the distribution
transparent to users.
Distributed data base
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Distributed data base
Advantages
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Advantages
Increase reliability and availability.
Easier expansion.
Improved performance
Reliable transactions
Economic
Disadvantages
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Disadvantages
Complexity
Security
Economics
Inexperience
Difficult to maintain integrity
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NORMALIZATION
Process of efficiently organizing data indatabase
Eliminating data redundancyReducing design flaws
How to achieve
Dividing database into two or more tables Defining relationship between them
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Why normalization
Normalization objective is to isolatedata so that additions, deletions and
modifications made in one table isapplicable to rest of tables in database
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NORMAL FORMS
Normal forms are applied to achievenormalized data
Normal forms are the conditions that atable should fulfill
Different types of normal
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Different types of normalforms
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)
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Different type of keys
PRIMARY KEY
COMPOSITE KEY
CANDIDATE KEY
SUPER KEY
FOREIGN KEY
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FIRST NORMAL FORM(1NF)
Each attribute must be atomic
No repeating columns within a row
No multi-valued columnsThis disallows “attribute as collection of
tuples”
Drawback Redundancy of data
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Examples of 1NF
Employee (unnormalized)
emp_no name dept_no dept_name skills1 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
Employee (1NF)
Emp-no name Dept-no Dept-name skills
1 Kevin jacobs 201 R&D CPerl
java
2 Barbara jones 224 IT Linuxmac
3 Jake rivera 201 R&D DB2OracleJAVA
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SECOND NORMAL FORM(2NF)
FUNCTIONAL DEPENDENCY:
This can be defined as every non-keyattribute is dependent on the primary keyattribute
PARTIAL FUCTIONAL DEPENDENCY
If an attribute is not dependent on all of
the keys in the relation, we say that it haspartial dependency on the key.
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Partial Functional Dependence
Skills is not functionally dependent on emp_no since it is notunique to each emp_no.
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 Java2 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
Employee (1NF)
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SECOND NORMAL FORM(2NF)
Meet all the requirements of 1NF
All partial dependencies must be
removed by dividing the table into smalltables and building relationshipsbetween them
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Example of 2NF
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 Linux2 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
Employee (1NF)
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 (2NF) emp_no skills
1 C
1 Perl
1 Java
2 Linux
2 Mac
3 DB2
3 Oracle
3 Java
Skills (2NF)
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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
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Third normal form(3NF)
Meet all the requirements of 2NF
Remove all transitive dependencies
Any transitive dependencies are movedinto a smaller (subset) table.
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Examples of 3NF
emp_no name dept_no dept_name1 Kevin Jacobs 201 R&D
2 Barbara Jones 224 IT
3 Jake Rivera 201 R&D
Employee (2NF)
emp_no name dept_no
1 Kevin Jacobs 201
2 Barbara Jones 224
3 Jake Rivera 201
Employee (3NF)
dept_no dept_name
201 R&D
224 IT
Department (3NF)
Boyce-codd Normal
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yForm(BCNF)
BCNF is based on the concept of a determinant (left hand attribute)
A determinant is any attribute (simpleor composite) on which some otherattribute is fully functionally dependent.
A relation is in BCNF if, and only if,every determinant is a candidate key.
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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
1 P
2 Q
3 R
4 S
5 P
ADVISOR MAJOR
P chemistry
Q Maths
R Social
S English
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Fourth Normal Fourth
Either of these conditions must hold true inorder to be fourth normal form
There is no multivalued dependency in the relation
There are multivalued dependency but theattributes are dependent between themselves
The relation must also be in BCNF
Fourth normal form differs from BCNF only inthat it uses multivalued dependencies
Multivalued
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Dependencies(MVD)
Given a relation R, let x and y beattributes of R. Then MVD denoted as
xy satisfied in relation R if t1(x)=t2(x)=t3(x)=t4(x)
t1(y)=t3(y) and t2(y)=t4(x)
x
y X Y Z tuplesa b1 c1 tuples-1
a b2 c2 tuples-2
a b1 c2 tuples-3
a b2 c1 tuples-4
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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:BC
FD:ABCD
As the relation has both FDs and MVDs it is in 4NF
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Fifth normal form(5NF)
Any remaining anomalies are removed