Introduction to DBMS

1. INTRODUCTION TO DATABASE
MANAGEMENT SYSTEM
STAFF-INCHARGE :
Mrs.S.SUBHASHINI MCA.,M.PHIL.,(SET)

2. INTRODUCTON :
• Data is a collection of facts such as numbers,
words, measurements, observations or just
descriptions of things.
* Information is processed data that put into
a meaningful and useful context to make best
decisions.
• It consists of data,images,text,documents,
voice,video etc.,
• It is a backbone of any organisation.
• It is a critical factor to gain competetive edge in
any organisation.
• It is most critical resource of an organisation.

3. Information cycle
• Input data are processed through models to
create information .
• Recipients receives information, makes
decision and then takes an action.
• Action triggers other action or events to
provide results.
• Resultant data are captured and can be used
as input data for other cycles

5. HISTORY OF INFORMATION
• In 4500 B.C ,clay tablets are used to record data.
• Clay tablets were used to store information
about receipts,disbursements, loans, purchases ,
sales, leases, partnership formation, contracts
etc.
• 500 yearsago, Inca indians of south america
used accounting apparatus called quipus.
• It consists of thousands of knotted strings and
• Knots were made in cords to represent units,
tens,hundreds etc.

6. HISTORY OF INFORMATION
Cords were differently colored to represent
lands,economic productivity , matters relatingto war
etc.
* Quipus were created & Maintained by high
officials like judges,commanders,family heads,
village head etc.,
*Art of data processing was already existed from
early ages.

7. HISTORY OF INFORMATION
Quipuamayus : People who built these
information system with knots was called “
Quipuamayus “
• All successful civilization had some kind of data
storage & retrieval system remains .
• Lot of information needed for internal decisions
& for successfully running organisation.

8. Quality of Information
• Quality information is accurate , timely and
relevant information.
* 3 Key attributes of information are
1. Accuracy
2. Timeliness
3. Relevancy
1.Accuracy :
- It means that information is clear and
accurate that reflects meaning of data.
- It also means information with no mistakes
and Error , free from bias.

9. 2.Timeliness :
• It means getting timely information with in
the needed time to the recipients.
. Recipients get timely information when they
want to use it at the very useful time.
3.Relevancy :
• It means use of a piece of information for a
particular person .
* Information relevant for one person might not
be relevant for another.
* Relevancy is a very subjective matter .

10. Information Processing
Definition :
Information Processing is the acquisition ,
storage, organisation, retrieval , display and
Dissemination of information .
* Few decades back , data processing was done
manually .
• Manual processing was good when amount of
data to be processed is less.
• punched cards ,magnetic tapes were used
( Initial Stage )

11. * Using punched cards, magnetic tapes only
batch processing of information was done .
• In this batch processing approach , individual
transaction is not managed .
• No possibility of giving answers quickly for
transactions in batch processing approach.
• Answers did not reflect current state of affairs
( might be a week (or) more out of date .

12. *In batch processing approach, relevancy of data
is maintained . But timeliness and accuracy of
information cannot be achieved .
*To overcome disadvantages of batch processing,
database approach can be used .
• Database approach is used to organise data in
an effective way than batch processing
approach .
• Database approach makes searching,
processing, retrieving of data very easy , quick
and effective.

13. Information and the enterprise
Enterprise : An Enterprise is the group of people
with a common goal and they uses certain
resources to achieve this goal .
*An enterprise acts as a single entity .
* In Traditional approach , an organisation is
divided in to different departments .
*Each department creates its own information
and generates its own.

14. *

15. • Information available only to top
management , but not to other departments.
• In Current Approach, Entire organisation is
considered as a system and all the
departments are its subsystems.
• Information of all subsystems stored
centrally .
• Made available to all departments
( subsystems ).
• Current approach helps organisation- move
forward as a single entity
effectively with central database.

17. Database
Definition: Database is a collection of data
designed to be used by different people .
• It has a collection of interrelated data stored together.
• It provides controlled redundancy of data .
• It can serve one or more applications.
• Data stored in database are independent of the
user programs .
• Organised way -A computer program quickly select
desired pieces of data.
• Traditional databases are organised by fields,
records and files.

18. Components (or) Elements of
Database
• A database consists of four elements .
1.Data
2.Relationship
3.Constraints
4.Schema
1.Data:
* Data is a collection of facts such as numbers,
words, measurements, observations or just
descriptions of things.

19. • Data exist in various form such as numbers ,text , bits,
bytes, images etc.
• Stored in binary form in computer memory.
• Stored as bytes in electronic memory.
• Stored as facts in person’s mind .
• In DBMS,Data files are the files that store the
database information.

20. * Indexfile , data dictionaries store administrative
information known as metadata.
Metadata : Meta data is an administrative information
Stored in index file , data dictionaries etc.
* It is data about data .
2.Relationship:
* It represent a correspondance between the
various data elements.
3.Constraints :
* constraints are predicate that define correct database
states.

21. 4. Schema : Describes organisation of data &
relationships with in the database .
*Defines various views of databases .
• Separates physical aspects of data storage from logical
aspects of data representation.
• Three schema are
a) Internal schema :
Defines how & where data are organised in physical
data storage .

22. b)Conceptual schema :
Defines stored data structure in terms of database
model used.
c)External schema :
Defines a view ( or) views of the database for
particular user.