DATABASE MANAGEMENT

SYSTEM
III SEMESTER
Learning Objectives

At the end of this chapter you will be able to know about:

 Database
 Properties
 Types of Database
 DBMS
 Purpose of DBMS
 Functionalities of DBMS
Data - Facts that can be recorded.
Example: texts, numbers, alphanumeric, audio, video,
image.

Information – Processed Material which has some meaning.

Example : The average score of a class is information
derived from the given data.
Database

Database is a collection of related data.

Example: A company database may include tables for

products, employees, financial records.
Database Properties

 It represents some aspects of the real world, called

mini world. Changes to the mini world are reflected in
the database.

 It is a logically coherent collection of data.

 It has a purpose: there is an intended group of users.

 What is DBMS

 A Database Management System (DBMS) is a collection

of programs enabling users to create and maintain a
database.

 Some DBMS examples include MySQL, PostgreSQL,

Microsoft Access, SQL Server, FileMaker, Oracle, RDBMS,
dBASE, Clipper, and FoxPro.
Why do we need DBMS
A database management system is
important because it manages data efficiently
and allows users to perform multiple tasks with
ease.

A database management system stores,

organizes and manages a large amount of
information within a single software application

A database together with the DBMS software is

referred to as a Database System.
Database + DBMS =DBS
 Typical DBMS Functionalities
 Defining
 Constructing
 Manipulating
 Sharing

Other Functionalities
Protection or Security
Presentation and Visualization of Data
Database Defintion

 Defining Database?
 Specifying the data types,
structures and constraints of the
data to be stored in the
database.
Database Construction

 Database Construction?
 Constructing the database is
the process of storing the data
on some storage device.
Database Manipulation

 Database Manipulation?
 Manipulating a database includes
functions such as querying the
database , updating the data etc.
Database Sharing

 Database Sharing?
 Sharing a database allows multiple
users and programs to access the
database simultaneously.
DATABASE MANAGEMENT
SYSTEM
Simplified Database System Environment
Users/Programmers
Database
System
Application Programs / Queries

DBMS
Software Software to Process
Queries / Programs

Software to Access Stored Data

Stored Database
Definition (meta Stored Database
- Data)
Characteristics of the Database
Approach

Self Describing Nature of a Database System

Insulation between Programs and Data, and Data Abstraction

Support of Multiple Views of the Data

Sharing of Data and Multiuser Transaction Processing

Self Describing Nature of a Database
System
A fundamental characteristic of the Database approach is
that the Database System contains not only the database
itself but also a complete definition or description of the
database structure and constraints.

The information stored in the catalog is called is called as

meta-data, describes the structure of the primary
database.
Course Name Course No Credit Department
Data Structures BcaII201 4 BCA
Discrete Math101 5 Math
Mathematics
Table: Course
An Example of a Database Catalog
RELATIONS
Relation_name No_of_columns
STUDENT 5
COURSE 4
SECTION 4

COLUMNS
Col_name Data_type Belongs_to_relati
on
FirstName CHAR(30) STUDENT
Email CHAR(30) STUDENT
YearofBirth INTEGER(4) STUDENT
COURSENO CHAR(5) COURSE
Example of Meta Data
Insulation between Programs and Data,
and Data Abstraction

In file system if some changes are made in the file structure,

then to handle these changes, more changes have to be made in
all the programs that access this file.

For example: If you want to add a piece of data, say date of

birth of students. Just adding it is not enough, the whole
program will have to be re-written to make it work.

But in a Database system all you need to do is define another

data item in the catalog called date of birth and all the changes
will be reflected and there is no need to change the whole
program.
Program-data independence refers to the capability
of leaving data intact and accessible regardless of
modifications to the database that contains the data.

Data Abstraction : A data model is used to hide

storage details and present the users with a
conceptual view of the database.
Support of Multiple Views of the Data
A database has multiple users, each user may
need different views or perspectives of the
database.

Database “view” can be the information that is

stored in the database or is derived from the
database.
Example: student table contains six fields

Student_nam Reg_no Course DOB Contact_no Address

e
Kiran 1101 CSE 11/1/1996 1234567890 Hubli
Anita 1305 MECH 27/10/1996 2134324356 Dharwad
Divya 2114 Civil 27/09/1995 9878675435 Belgaum
Query to do this task: select Student_name, Contact_no, Address
from student;
Student_name Contact_no Address
Kiran 1234567890 Hubli
Anita 2134324356 Dharwad

Query: select Student_name, Reg_no from student;

Student_name Reg_no
Kiran 1101
Anita 1305
Divya 2114
Sharing of Data and Multiuser
Transaction Processing
A multiuser DBMS must allow multiple users to
access the database at the same time.

This is essential when single database is maintained

for multiple applications.

The DBMS must include concurrency control, which

is supposed to ensure that the information is correct
when multiple users try to access and update the data.
DATABASE MANAGEMENT
SYSTEM
Introduction Continued…
Users of Database
Users of the database mainly divided into two
categories.

• Actors on the scene

1.

• Workers behind the scene

2.
Actors on the scene
1. Database Administrator (DBA) :

DBA’s are the chief administrators, who oversees and

manages the database system (including the data and
software).

DBA is responsible for following duties:

Authorizing users to access the database.

Coordinating/monitoring database use.
Acquiring hardware/software as needed.
2. Database Designers

They are responsible for identifying the data to be stored.

Responsible for choosing an appropriate way to organize

the data.

They also define views for different categories of users.

The final design must be able to support the requirements

of all the user sub-groups.
3. End Users

These are persons who access the database for querying,

updating, and report generation.
End Users are those who access the database from the
front end. They use the developed applications & they
don’t have any knowledge about the design & working
of Database.
Their main aim is to get their task done.
There are several categories of end users:

Casual end users

Naive/Parametric end users

Sophisticated end users

Stand-alone users
Casual User

 Occasionally access Database.

 Need Different information each time.
Naïve User
 User who does not have any knowledge
about DB.
 Their task is to use the developed
application and get desired output.
 Example : Bank Management System,
Library Managemnt System
Sophisticated Users

 Have knowledge of query language. So they

use database query language to access
information from DB to meet their
complicated requirements.

 Example : Business Analyst, Scientist etc.

Standalone Users

 Maintain Personal Database by using ready

made Program packages that provide easy
to use Menu based or graphical based
interfaces.
 Example: Financial Software Packages.
4. System Analysts

System Analysts:
Determine needs of end users, especially naive and
parametric users, and develop specifications for canned
transactions that meet these needs.
Determine the requirements of the end user to create a
solution for their business needs

Application Programmers:
Implement, test, document, and maintain programs that
satisfy the specifications mentioned above.
Workers behind the Scene
DBMS System Designers/ implementers :
These are persons who design and implement the
DBMS modules and interfaces as a software package.

Tool Developers :
Design and implement software tools facilitating
database system design, performance monitoring,
creation of graphical user interfaces, prototyping etc.

Operators and maintenance Personnel :

Responsible for day-to-day operation of the system.
Controlling Redundancy

Restricting Unauthorized Access

Providing Persistent Storage for Program Objects

Providing Storage Structures for Efficient Query Processing

Providing Backup and Recovery

Providing Multiple User Interfaces

Representing Complex Relationships among Data

Enforcing Integrity Constraints

Permitting Inferencing and Actions Using Rules

Controlling Redundancy

Data redundancy occurs when same data is

stored multiple times.

Redundancy leads to several problems:

Duplication of effort

Storage space is wasted

Inconsistency
The file based data management systems contained multiple
files that were stored in many different locations in a system
or even across multiple systems. Because of this, there were
sometimes multiple copies of the same file which lead to data
redundancy.

This is prevented in a database as there is a single database

and any change in it is reflected immediately. Because of this,
there is no chance of encountering duplicate data.
Example
Restricting Unauthorized Access

When multiple users share a database, it is likely that some users

will not be authorized to access all information in the database.

For example, account office data is often considered confidential,

and hence only authorized persons are allowed to access such
data.

Some users may only be permitted to retrieve data, whereas

others are allowed to retrieve and update.

A DBMS should provide security and authorization subsystem.

Can you Analyze this
Diagram?
Providing Persistent Storage for
Program Objects
Persistent storage is any data storage device that retains data
after power to that device is shut off. It is also sometimes
referred to as non-volatile storage.

Databases can be used to provide Persistent storage for

program objects and data structures.

Object oriented database systems make it easier for complex

runtime objects and data structure(lists, trees) to be saved in
secondary storage so as to survive beyond program
termination and to be retrieved at a later time.
Providing Storage Structures for
Efficient Query Processing

Database systems must provide capabilities for

efficiently executing queries and updates.

The DBMS maintains indexes(typically in the form

of hash tables) that are utilized to improve the
execution time of queries and updates.

The query processing and optimization module of

the DBMS is responsible for choosing an efficient
query execution plan for each query submitted to
the system.
 Basic steps in Query Processing

Parser and Relational Algebra

Query Expression
Translator

Evaluation
Query Optimizer
Engine
Output

Execution Plan

Data Statistics
Providing Backup and
Recovery

Backup : A copy of data that is used to restore the original after a

data loss event occurred.

Recovery : Process of retrieving inaccessible, lost, corrupted,

damaged data to the original state.

DBMS should provide backup facilities to assist with the

recovery of a database failure.

Backup and Recovery refers to the various strategies and

procedures involved in protecting your database against data loss
and reconstructing the database after any kind of data loss.
Providing Multiple User Interfaces

Many types of users with varying levels of technical

knowledge use a database, A DBMS should provide a
variety of user interfaces.

Query languages for casual users.

Programming language interfaces for application

programmers.

Forms and command codes for parametric users.

Menu driven interfaces and natural language interfaces

for stand alone users.
Representing Complex
Relationships among Data

A database may include numerous varieties of

data that are interrelated in many ways.

A DBMS should have the capability to

represent such relationships and to retrieve
related data quickly.
Enforcing Integrity Constraints

Integrity of data means that data in database in always

accurate.

Integrity constraints are enforced on database.

In file system this constraint must be enforced in all the

application separately.

In case of DBMS this integrity constraint is applied only once

on the field.
Example

Let us consider the case of college database

and suppose that college having only Btech,
Mtech, MCA, Msc, BCA, BBA and B com.

But if a user enters the class MS, then incorrect

information must not be stored in database and
must be prompted that this is an invalid entry.
Integrity is to be enforced on the class attribute.
Permitting Inferencing and Actions Using
Rules

In a deductive database system, one may specify

declarative rules that allow the database to infer new
data!
Example : Figure out which students are on academic
probation.

More powerful functionality is provided by active

database systems, which provide active rules that can
automatically initiate actions when certain events and
condition occur.
Difference between DBMS and Flat File
Management System

DBMS Flat File Management System

Multi-user access It does not support multi-user access

Design to fulfill the need for small It is only limited to smaller system.
and large businesses
Remove redundancy and Integrity Redundancy and Integrity issues

Expensive. But in the long term It's cheaper

Total Cost of Ownership is cheap
Easy to implement complicated No support for complicated
transactions transactions
Additional Implications of Using the
Database Approach

Potential for Enforcing Standards

Reduced Application Development Time

Flexibility

Availability of Up-to-Date Information

Economies of Scale
Potential for Enforcing Standards :

This facilitates communication and cooperation among various

departments, projects, and users within the organization.

Standards can be defined for names and formats of data

elements, display formats, report structures, and so on.
Reduced Application Development Time:

A prime selling feature of the database approach is

that developing a new application takes very little
time.

Designing and implementing a new database from

scratch may take more time than writing a single
specialized file application.
Flexibility :

It may be necessary to change the structure of a database as

requirements change.
But modern DBMS allow certain types of evolutionary changes
to the structure of the database without affecting stored data and
the existing application programs

Availability of Up-to-Date Information :

A DBMS makes the database available to all users.

As soon as one user’s update is applied to the database, all other
immediately can see this update.
Economies of Scale :

The DBMS approach permits consolidation of data and

applications, thus reducing the amount of wasteful overlap
between activities of data processing in different projects or
departments as well as redundancy among applications.

This enables whole organization to invest in more powerful

resources rather than having own equipment. This reduces
overall costs of operation and management.
When not use a DBMS?

There are few situations in which such a system may

involve unnecessary overhead costs that would not be
incurred in traditional file processing.

The overhead costs of using a DBMS are due to the

following:

High initial investment and possible need for

additional hardware.

Overhead for providing generality, security,

concurrency control, recovery, and integrity functions.
When DBMS may be unnecessary :

If the database and applications are simple, well

defined, and not expected to change.

If there are stringent real-time requirements that

may not be met because of DBMS overhead.

If access to data by multiple users is not required.

A collection of related data.

a) Information

b) Valuable information

c) Database

d) Metadata
DBMS is software?

a) True
b) False

Which of the following is not involved in DBMS?

a) End Users

b) Data

c) Application Request

d) HTML
The restrictions placed on the data.

a) Relation

b) Attribute

c) Parameter

d) Constraint
DBMS manages the interaction between __________ and
database.

a) Users

b) Clients

c) End Users

d) Stake Holders
The following are components of a database
except ________

a) user data

b) Metadata

c) Reports

d) indexes
An application where only one user accesses the database at a
given time is an example of a(n) ________

a) single-user database application

b) multiuser database application

c) e-commerce database application

d) data mining database application

These users who access the database occasionally but they
need different information each time.

a) Parametric end users

b) Casual end users

c) Sophisticated end users

d) None of these
Thank you…..

Any Queries?
If any Questions ?