1_dbms_introduction.ppt

7/27/2019 1_DBMS_Introduction.ppt

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DATABASE

MANAGEMENT SYSTEM


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DATABASE

MANAGEMENT SYSTEM

A database

system is

basically a

computer

based record

keeping

system

A DBMS is a

collection of

interrelated

data and a set

of programs to

access those

data

The primary

goal of a DBMS

is to provide a

way to store

and retrieve

database

information


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Basic Terms

Data

Information

Database

Database System


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Basic Terms

Data

Information

Database

Database System

Anything can be a data.

(raw facts & figures)


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Basic Terms

Data

Information

Database

Database System

Processed data.

(meaningful data)


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Basic Terms

Data

Information

Database

Database System

A computer based recordkeeping system, whose overall

purpose is to record and

maintain information. It

manages the database of an

enterprise.


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What is the need of a Database

Management System ?


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File based systems are an early attempt to computerise the

manual filing system.This works well when the number of

items to be stored is small or the process is only needed to

store and retrieve information.

The File Based System


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Students

Courses

Students

Fee

Collection

Faculty

Subject DepartmentApplication by C program

Application by COBOL program

University


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Database System vs. File Based System


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Limitations of File Based System

Separation and Isolation of Data

Duplication of Data Inconsistent Data

Data Dependence

Incompatible File Formats Fixed Queries


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Data Dependence


When the data is stored in

separate files it becomes

difficult to access.


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Data Dependence


Decentralised approach leads

to uncontrolled duplication ofdata, which leads wastage of

storage space, time and

money.


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Data Dependence


Changes made by different

people for the same informationdifferently or Entering a wrong

data.


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Data Dependence


The physical structure and

storage of data files andrecords are defined in the

application code.

Program Data Dependence


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Data Dependence


The structure of the fileembedded in application

program totally dependent on

the programming language.

This incompatibility makes

them difficult to process jointly.


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Database System

Data

Hardware

Software

Users

A database system involves four major components

Provides the enterprise with centralized

control of its data.


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Database System

Data

Hardware

Software

Users

A database system involves four major components

Provides the enterprise with centralized

control of its data.

A database contains not only the data

but also the complete definition of the

database structure and constraints.


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Advantages of Database Approach

Redundancy can be reduced

Inconsistency can be avoided

The data can be shared

Standard can be enforced


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In a file processing system, each user group maintains

its own files, resulting in a considerable amount of

redundancy of the stored data. In database approach

data can be stored at a single place or with controlledredundancy under DBMS.


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A database is said to be inconsistent, when there will

be occasions on which the redundant entries will not

agree. A database that is in an inconsistent state is

capable of supplying incorrect or conflict information.


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A DBMS allows the sharing of database under its

control by any number of applications programs or

users. The data requirements of new applications may

be satisfied without having to create any new storedfiles.


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With central control of the database, the DBA can

ensure that all applicable standards are followed in the

representation of the data.

Standards => company, installation, departmental,

industry, national and international standards.


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Data Independence

Security restrictions can be applied

Integrity can be maintained

Multiple user interfaces

Continue


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Data Independence

Security restrictions can be applied



Continue

Data Dependence => the knowledge of the data

organization and access technique is built into the

application logic. It is impossible to change the storage

structure or access strategy without affecting theapplication.


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Advantages of Database Approach Data Independence

Security restrictions can be

applied



Continue

DBA can define authorization checks to be carriedout whenever access to sensitive data is attempted

Different checks can be established for each type of

access to each piece of information in the database.


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applied



ContinueData integrity refers to the correctness and completeness of data in a

database=> by providing

Checks

Constraints(to data items within a record or relationships between records)


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applied



Continue

A DBMS provides a variety of interfaces Query language

Programming language interfaces

Forms and codes

Menu driven interfaces


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Advantages of Database Approach Improved Backup and Recovery

Support for Concurrent Transactions

Conflicting requirements can be

balanced

Continue

A backup and recovery subsystem is responsible for

recovering data from hardware and software failures.


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Advantages of Database Approach Improved Backup and Recovery


Conflicting requirements can be

balanced

Continue

A DBMS allows multiple transactions to occur

simultaneously.


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Improved Backup and Recovery


Conflicting requirements can be balanced

Continue

By knowing the overall requirements of the enterprise

the DBA can structure the database system to provide

an overall service that is best for the enterprise.

1_dbms_introduction.ppt

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