Data

503. DATA BASE DESIGN

LBSITW TRIVANDRUM, Department of Computer Science 1



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DATA:

It can be figures,numbers,quantity anything

Recorded Information

They have implicit meaning

Ex: Varna chithra, 100, 13, etc….

INFORMATION

It is meaning full and arranged

data

Ex: Name = Varna chithra

No : of cars = 100

Age = 13

KNOWLEDGE

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



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

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



1. Centralized control:

Centralized control of the data

2. Redundancy can be reduced:

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.



3. Inconsistency can be avoided

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

Admin can enforce standard

Ex: ID generation of staff in college

6. Security restriction can be applied

Only access through proper channel

Different types of access can be provided

(retrieve, modify, delete, create etc...)

7. Integrity can be maintained

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

Understanding the requirement correctly.



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 For production(in factory),inventory(in ware

house).order, supply chain

ONLINE RETAILERS For Order tracking, customized

recommendation

MANUFACTURING For Customer ,product, purchases

HUMAN RESOURCES Employee records, salaries, tax reduction

AIRLINES For Reservation ,schedule information etc

UNIVERSITIES For Registration(student) ,grade etc

BANKING For customer account ,loans, banking

transaction etc

TYPES OF DATABASE

Centralized Distributed

The entire data is located at a single site

Allow for greater control over

accessing and updating data

Ex: Bank ATM system

The data base is stored on several

computer or mainframe system

The computer in a distributed system

can communicate with each other via

various communication media(high

Speed network or telephone lines)

Ex: A multinational banking system.

The bank database distributed across

different branches.



Centralized

Distributed



DATA BASE MANAGEMENT SYSTEM

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



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

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

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



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

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.



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



Detailed figure of Three schema architecture



DATA BASE USERS

Mainly categorized into three main categories

I. End user

II. Application programmer

III. Data Base Administrator



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.

Data

Education

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