MIS 710 Module 0Database fundamentals

Arijit Sengupta

ISOM

Structure of this semester

Database Fundamentals

Relational Model

Normalization

ConceptualModeling Query

Languages

AdvancedSQL

Transaction Management

Java DB Applications –JDBC

DataMining

0. Intro 1. Design 3. Applications 4. AdvancedTopics

Newbie Users ProfessionalsDesigners

MIS710

2. Querying

Developers

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Today’s buzzwords

• Organizational data cycle• Database• Database Management Systems• Data Independence• Centralized Database Systems• Client-Server Database Systems• Distributed Database Systems

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Objectives of today’s lecture

• Know common database terminology• Understand requirements and uses of data• Know the differences between databases

and flat files• Realize the importance and need for

databases in problem-solving• Understand the different types of

databases and their differences

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Data: A Resource

• The Success of an organization depends on efficient use of its resources:Buildings, factories, equipmentTechnical know-howHuman resourcesData

• Data: An important organizational resource

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The Organizational Data Cycle

User Decisions

Knowledge

InformationData

Actions

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Electronic Data

• Why?Large volume in a small spaceEase of sharingEase of useData analysis

• How?File-based system versus databases

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Legacy (File-based) Systems

• Uncontrolled data redundancy, • Data inconsistency• Poor data sharing• Difficult to keep up with changes• Record format Vs. user requirements• Programs Vs. record format• Low productivity• High maintenance cost

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So what is a database?

• According to Oxford English Dictionary:“A structured collection of data held in

computer storage; esp. one that incorporates software to make it accessible in a variety of ways”

• So does it make pretty much every collection of data a “database”?

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The Database

• The data itself PLUS The data definitions (metadata), applications, queries and visualizations

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Database Approach

• Non-redundant collection of logically related facts representing some aspect of the real world the data itself plus the data definitions

• Permits sharing• Consistent representation for each piece of data• Avoids (minimizes) redundancy• Allows different user views• Users are isolated from most changes

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Why Databases?

• Independence from representation formats

• Control redundancy and consistency• Ensure integrity/security• Better scalability• Allow ad hoc access• Better maintenance• Better concurrency

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Data Independence

• Does data have to be part of programs?

• Do we need to change one if the other changes?

• Three-tier architecture of databasesWhat the users see

How we model data

How data is stored

View

Conceptual

Physical

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Access Flexibility

• Easy to ask ad-hoc questions

• No need for separate codes

• User-friendly interface

• Command-based (e.g., SQL)

• Graphical (e.g., QBE)

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Data Integrity

• Ensures that the stored data are consistent and correct

• Easy to define global rulescustomer_age > 21 yearsnumber_of_credits < 18

• Can allow multiple users to access data without compromising on data integrity

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Data Security

• Access definitionGlobalLocal

• Uniform access authorization

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Data Redundancy

• Data need not be replicated

• Less wastage of storage space

• Less data anomaly

• Reduced and controlled redundancy

• Tighter control of replicated data

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Standardization

• Everybody talks the same talk.Less chance of misunderstandingEasier to interpret other’s data

• Easier to mergeUseful when several organizations

combine to form one.

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Productivity and Maintenance

• Increase in productivity User-friendly interface Independence from specific data structure

• Easier maintenance Less code to maintain

• The DBMS is the bulk of the code.• Ad-hoc queries make it possible to make do with

much less code. The vendor makes revisions of the DBMS.

• Economy of scale

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Productivity vs. Maintenance

0102030405060708090

100

Start 1st week 2nd week 3rd week 4th week

Prod-DB

Prod-FL

Mnt-DB

Mnt-FL

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Disadvantages of Databases

• Software complexity

• Processing inefficiency

• Need for co-ordination

• Organizational impact

• Risk

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DBMS

• A Specialized piece of software that sits between the data and its users.

DatabaseManagement

System

DataIntension + Extension

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DBMS Functions and Users

• Four major uses of a DBMS package Database Development, Interrogation, Maintenance,

and

Application Development

• Automated tools for design, query, and application development

• Database users Database administrators ( DBAs )

Database designer

End Users

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Centralized Database Systems

Database

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Client/Server Database Systems

DatabaseServer

Client

Client

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Distributed Database Systems

DatabaseServer

DatabaseServer

DatabaseServer

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Summary

• Data is essential for an organization

• A Database is usually the most effective way of storing and organizing data

• File-based Vs. database systems

• Database system properties

• Types of database systems