Data

503. DATA BASE DESIGN

LBSITW TRIVANDRUM, Department of Computer Science

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DATA:
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It can be figures,numbers,quantity anything
Recorded Information
They have implicit meaning
Ex: Varna chithra, 100, 13, etc….

INFORMATION
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data
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It is meaning full and arranged
Ex: Name = Varna chithra
No : of cars = 100
Age = 13

KNOWLEDGE
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How we apply our information in a situation
It is paired, shaped, interpreted, selected and transformed.
Why we need information
 Addition Knowledge : How much of information in our hand
that much of knowledge
: More information more chance to apply for

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knowledge
 Decision making: Information are helpful in making good decision at right time
 Can apply in different levels : Used for different purpose like weather forecasting,
result analysis etc
 Increase in productivity: Avoid waiting of time, money, effort etc...
DATA BASE
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Organized collection of inter related data stored
together with controlled redundancy.
Collection of data designed to be used by different
people.
Data are stored in such a fashion that they are
independent of the programs of people using the data
The data in the data base is integrated, which means
that the database is a collection of distinct (not
identical) files.
These distinct files may have some duplicate data but
the duplication of data is to the minimum.
Thus data in the database
 Is Integrated
 Can be Shared
 Can con currently accessed

ADVANTAGES OF HAVING DATA IN DATABASE or ADVANTAGES OVER
TRADITIONAL FILE SYSTEM

1.
Centralized control
2.
Redundancy can be reduced
3.
Inconsistency can be avoided
4.
Data can be shared
5.
Standard can be enforced
6.
Security restriction can be applied
7.
Integrity can be maintained
8.
Conflicting requirements can be balanced


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1. Centralized control:
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Centralized control of the data

2. Redundancy can be reduced:
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Redundancy of data means repetition of the data
So maximum it avoid multiple copies
Note: Sometimes redundancy allowed, because technically & business reasons we need
to store multiple copies.


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3. Inconsistency can be avoided
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It is corollary to the above statement.
If same data is duplicated and change made to one of
them lead to inconsistency.

4. Data can be shared
 More than one persons can
access the same data or different data at same time
 Information is shared

5. Standard can be enforced
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Admin can enforce standard
Ex: ID generation of staff in college

6. Security restriction can be applied
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Only access through proper channel
Different types of access can be provided
(retrieve, modify, delete, create etc...)

7. Integrity can be maintained
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It means data are accurate
Permits admin to define constraints to the
data base
Ex: Admin adding a constraint “Minimum
balance need to change an account to cheque
book account is 1000 RS.

8. Conflicting requirement can be balanced
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Understanding the requirement correctly.


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CHARACTERISTICS OF DATA IN DATABASE
It should have the following features(we already discussed about
this)
1. Shared
2. Persistence : It means the data exist
permanently ,beyond the scope of the
process
3. Validity/Integrity/Correctness
4. Security
5. Consistency
6. Non- redundancy
7. Independence : ( we will discuss it later)
DATA BASE SYSTEM APPLICATIONS
Some representative applications are
SALES
ONLINE RETAILERS
MANUFACTURING
HUMAN RESOURCES
AIRLINES
UNIVERSITIES
BANKING

For production(in factory),inventory(in ware
house).order, supply chain
For Order tracking, customized
recommendation
For Customer ,product, purchases
Employee records, salaries, tax reduction
For Reservation ,schedule information etc
For Registration(student) ,grade etc
For customer account ,loans, banking
transaction etc

TYPES OF DATABASE
Centralized
Distributed
 The entire data is located at a single site
 The data base is stored on several
computer or mainframe system
 Allow for greater control over
accessing and updating data
 The computer in a distributed system
can communicate with each other via
 Ex: Bank ATM system
various communication media(high
Speed network or telephone lines)
 Ex: A multinational banking system.
The bank database distributed across
different branches.


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Centralized

Distributed


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DATA BASE MANAGEMENT SYSTEM
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It is a collection of programs that enables you to store ,modify data and
extract information from a database.
It varies from small to large
It is a piece of software that provides services for accessing a database
Components of DBMS are

A. Transaction Management
 Transaction: Sequence of database operation that represent a logical unit of
work
 Access and transform database from one state to another
 Include update, delete, modify a set of records
 If we want to save a transaction just do ‘commit’
 If don’t want that change just rollback
B. Concurrency Control
 Operate concurrently that access shared data and can potentially interface with
one another
 Goal: Allow concurrency while maintaining
the consistency of shared data.
C. Recovery Management
 Ensures that database is returned to a
consistent state even after the failure or aborts
 More concurrency more is the chance that an

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aborted transaction
D. Security Management
 Protection of data against unauthorized access
 DBA give different access privileges to the users
E. Language Interface
 Provide support languages
 These languages are used for definition and manipulation of data in the
database.
o Data Structure Creation : Used
DDL(Data Definition Language)
o Manipulation of Data : Used
DML(Data Manipulation
Language)
F. Storage Management
 Permanent storage of data
G. Data Catalog Management
 Also known as data dictionary
 It contains the metadata (data
about the data , it actually
contains description of the data)
 These are helpful to know the structure

SCHEMAS AND INSTANCES
INSTANCES
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The collection of information stored in the database at a particular moment is
called an instance of the database.
Database change over time as information is inserted and deleted.
The value of variable in the program at appoint in time correspond to an
instance of a database schema.

SCHEMA
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The overall design of the database is called the database schema
Schemas are changed infrequently
Data base system have several schemas ,portioned according to the levels of
abstraction

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 Physical schema : It describes data base design at physical level
 Logical schema : It describes data base design at logical level.
 Sub schemas
: Database design at view level
THREE -SCHEMA ARCHITECTURE
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Also known as 3-Level
architecture of a DBMS or
ANSI –SPARC Model
ANSI_- American National
Standard Institute
SPARC-Standard Planning
And Requirements
Committee.
Most modern commercial
DBMS are based on this
system

OBJECTIVES
1. It allows independent customized user views:
 Each user should be able to access the same data, but have a different
customized view of data.
2. It hides the physical storage details from user:
 Users should not have to deal with physical database storage details.
 They should be allowed to work with the data itself,without concern
for how it is physically stored.
3. The database administrator should be able to change the database storage structure
without affecting the user’s view:
 From time to time rationalization or other changes to the structure of
an organization’s data will be required.

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4. The internal structure of the database should be unaffected by change to the
physical aspects of the storage
 Change over to a new disk.
5. The database administrator should b able to change the conceptual or global
structure of the database without affecting the users
 This should be possible while still maintaining the desired individual
users view.

Fig: Three -Schema Architecture


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Detailed figure of Three schema architecture


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DATA BASE USERS
Mainly categorized into three main categories
I.
II.
III.

End user
Application programmer
Data Base Administrator


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I.

End user
 Deals only with the higher level of abstraction
 They may not be concerned with or even aware of the
details of the DBMS
 The end users involved in updates to the database or
queries on the database.
 Categories of end users are.
 Casual end user: Access database occasionally
when needed.
 They need different information each
time.
 Thy uses a sophisticated database query
language to specify their request.
 Naïve or parametric users.
 Users who interact with the system by
involving one of the application programs
that have been written previously.
 They make up a large section of the end
user population.
 These are the users who communicate
with the database on regular period.
 Their job is to constantly querying and
updating the database using the standard
queries. This is called canned transaction.
 Ex: Bank teller, Reservation clerks etc.
 Sophisticated users
 These include business analyst scientist,
engineers, and other thoroughly familiar
with the system capacity.

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