DATABASE MANAGEMENT

WHAT IS DATABASE
MANAGEMENT ?
1DATABASE MAGEMENT SYSTEM

SOME BASIC CONCEPT
What is a data?
Data is collection of facts and figures
which can be processed to produce
information.
What is a database?
A database is a collection of data

DATA BASE MANAGEMENT SYSTEM
(DBMS)
A DBMS is a collection of data which
 Provide management of databases
 Used to store, update, retrieve,manipulate & helps
to produce information.
 Control access to data
 Provide convenient & efficient to retrieve data
 Supports secure, atomic access to very large
amounts of data.

 provide concurrent access (different users at
the same time).
 Provides an interface between users and the
database
 Backup and Recovery in event of a system
failure.
 Security - password allocation and access
rights to particular layouts.

APPLICATION
 SALES: For customer, product, and purchase
information.
 ACCOUNTING: For payments, receipts, account
balances, assets and other accounting
information
 HUMAN RESOURCES: For information about
employees, salaries, payroll taxes and benefits,
and for generation of paychecks.
 BANKING: For customer ,information, account,
and loans, and transaction.

 CREDITS CARD TRANSACTION: For purchases on
credits cards and generation of monthly
statements.
 UNIVERSITIES: For students information, course
registration, and grades.
 AIRLINE: For reservation and schedule
information. Airline were among the first to use
database in a geographically distributed manner
terminals situated around the world accessed
the central database system through phone lines
and other data network.

PURPOSE OF DBMS
 Provides secure and survivable medium for
storage & retrieval of data
 Data shared among several users & is persistent
 Provides mechanism to create, access and
manipulate data without compromising security
and integrity of data
 Redundancy can be reduced
 Inconsistency can be avoided

CONVENTIONAL FILE PROCESSING
SYSTEM
VS
DATABASE SYSTEM

o A data can be stored in either
CONVENTIONAL FILE PROCESSING SYSTEM or
a DATABASE SYSTEM
o In conventional file processing system,
each & every subsystem of the
information will have its own set of files.
As a result, there will be duplication of
data between various subsystems.
o But in database systems, there is a single
centralized database which minimizes the
redundancy of data to a greater extent.

File processing system
• File processing system- stores permanent
records in various files, & it needs different
application programs to extract records from,
and add records to, the appropriate files.

Disadvantages of File processing
system
Data redundancy and inconsistency
Difficulty in accessing data
Data isolation
Integrity problems
Atomicity problems
Concurrent-access anomalies
Security problems

Data redundancy and inconsistency
• Data redundancy - Same information may be
duplicated in several places. e.g. Customer Name, NI
number, Address is present in several different files on
several different systems. Errors are generated, time
entering data is wasted, computer resources are
needlessly taken up and updates can be an enormous
problem.
• Data inconsistency All copies may not be updated
properly it will become a problem e.g. information is
duplicated in each system and may be updated in most
systems but not necessarily in all – the savings account
and loan account may have different addresses for a
particular customer.

Difficulty in accessing data
• May have to write a new application program
to satisfy an unusual request.
• E.g. find all customers with the same postal
code.
• Could generate this data manually, but a long
job...

Data isolation
• Data in different files.
• Data in different formats.
• Difficult to write new application programs.

Integrity problems
• Data lacks integrity , i.e. this is the quality by which
information from the system can be trusted. The
problems already stated show that information can be
out of date, can have different values in different parts
of the system, can be inaccurate etc.
• Data may be required to satisfy constraints.
• E.g. no account balance below $25.00.
• Again, difficult to enforce or to change constraints with
the file-processing approach.

Atomicity problems
• Transfer of funds from one account to
another should either complete or not
happen at all

Concurrent-access anomalies
• Concurrent accessed needed for performance
Uncontrolled concurrent accesses can lead to
inconsistencies
• Example: Two people reading a balance and
updating it at the same time

Security problems
• Lack of security i.e. there are no restrictions on
who can see what.
• Every user of the system should be able to access
only the data they are permitted to see.
• E.g. payroll people only handle employee records,
and cannot see customer accounts; tellers only
access account data and cannot see payroll data.
• Difficult to enforce this with application
programs.

REFERENCE BOOKS:
• 1. DATABASE SYSTEM CONCEPTS (6th edition),
by Abraham Silberschatz, Henry F. Kroth & S.
Sudarshan, McGRAW-HILL
• 2. DATABASE MANAGEMENT SYSTEM by
Seema Kedar, Technical publication

DATABASE MANAGEMENT

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