Database Systems

(CS F212)
Prof.R.Gururaj
BITS Pilani CS&IS Dept.
Hyderabad Campus
Introduction DBMS Concepts and
Architecture(Ch.1 & 2 of T1)
Content
❑ Database Systems and Significance
❑ Database System Applications
❑ DBMS
❑ Database system environment
❑ Advantages of DBMS over traditional file systems
❑ Database users
❑ Data model
❑ Data abstraction and three-schema architecture
❑ Data independence
❑ DBMS architectures
❑ Classification of DBMS

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Database Systems

Databases and Systems to manage them have become

significant components of any present day business of
any nature.

These databases help businesses to perform their day-

to-day activities in an efficient and effective manner.

Business; E-Commerce; Social media; Science and

Engg; Sports; Law, Education and so on….

Here some program access the database.

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

In the recent past, advances in technology has given
raise to new concepts-
✓ Multimedia databases
✓ GIS
✓ Web data
✓ Data warehousing and mining
✓ Big Data
✓ No-SQL Databases
✓ Distributed databases
✓ In memory databases
✓ Cloud databases
✓ Graph databases
etc.
Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus
Data: Known fact that can be recorded and that has
implicit meaning.
Ex. Name, Tel_no, city etc.

This data can be stored in a file on a computer.

Database: Is a collection of related data.

Generated and maintained manually or may be

computerized.

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Implicit properties of a Database

❖ Is a logically coherent collection of logically related

data. A random assortment of data cannot be refereed
to as a Database.

❖ Represents some aspect of the real world,

sometimes called as the miniworld OR universe of
discourse.

❖ Is designed, built and populated with data for a

specific purpose.

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Database Management
Systems (DBMS)
DBMS: Is a collection of programs that enables users to
create and maintain databases in a convenient and effective
manner.

DBMS is a software system that facilitates the following:

1. Defining the database

2. Constructing the database
3. Manipulating database for various applications
4. Sharing the database

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Database System

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Main characteristics of database approach versus file-
processing approach

❑ Self-describing nature of database systems

(meta-data)
❑ Insulation between programs and data
(program-data independence)
❑ Support multiple views of data
❑ Sharing of data and multiuser transaction
processing (ACID properties)

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Actors on the scene
DBA
❑ DB Designers
❑ Application Programmers (SW developers)
❑ End users- Naïve and Sophisticated

Actors behind the scene

DBMS developers
❑ Tool developers
❑ Operators and Maintenance Personnel- System
Administration team- mts of HW and SW

(Ref: Sec 1.4 & 1.5 of the Textbook)

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Advantages of storing data in a database using DBMS

❑ Control redundancy
❑ Providing storage structures and search techniques
❑ Backup and recovery
❑ Providing multiuser interface
❑ Representing complex relationships among data
❑ Integrity constraints
❑ Supporting Rules and Triggers
❑ Supports transaction management.

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Reading Assignment:
A Brief history of Database Applications
Sec. 1.7 of the Textbook.

BITS Pilani, Hyderabad Campus

Database System concepts
and
Architecture

(Ch.2 of T1)

BITS Pilani, Hyderabad Campus

 Data model

Database approach proves different levels of data

abstraction. What is data abstraction?

Data model Is a collection of concepts that can be used to

describe the structure of the database.
Structure means data types, relationships, constraints etc.
DBMS allows a user to define the data to be stored in terms
of a data model.
• High-level or Conceptual Data Models

• Representational or implementation Data models

• Low-level or Physical Data Models

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

The following are some important representational data models (DBMS Specific)

1. Network Model: Though the basic structure is a record,

the relationships are captured using links.
The database can be seen as an arbitrary network of records connected by links.
Ex.: GE’s Integrated Data store (IDS), in Early 1960s
2. Hierarchical Model: The records containing data are organized
as a collection of trees. Ex.: IBMs IMS (Information Management System),
in late 1960s
3. Relational Model: (early 1970s)Data & relationships are captured as tables & keys.
Ex.: Oracle, IBMs DB2, MySQL, Informix, Sybase, MS Access, Ingress, MySQL etc.
The basic storage structure is a record.
4. Object Data Model: Objects created through object–oriented programs
can be stored in database.
Ex.: Object Store
5. Object Relational Model: Objects can be stores in tables.
Ex.: Oracle, Informix

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Database Schema
Database Schema: Description of a database is called as database Schema

Three-Schema Architecture
A database can be described at three different levels.
Description at each level can be defined by a schema. At each level we focus on
one of the specific issues such as user views, concepts, storage etc.

1. External schema
2. Conceptual schema (logical schema
3. Physical schema

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Three Schema Architecture

External Schema 1 External Schema 2 External Schema 3

External Level

Conceptual Level Conceptual Schema

Physical Schema
Physical/Internal
Level

Storage

Three schema architecture of

DBMS

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Data Independence
Data Independence:
The three-level architecture which is the result of the three-level
abstraction on database, leads to data independence.

1. Logical data independence:

2. Physical data independence:

Metadata:
The DBMS stores the description of schema constructs, the constraints,
and other related info about the data in the DB. These descriptions are
called as metadata. Otherwise it can be seen as data about data.

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

DBMS Structure

Web form Application SQL

front end interface

SQL
Command
s

Query Engine

Transaction
Manager
Recovery
Buffer / Disk / File Manager
Lock Manager
Manager

Concurrency
control manager

DBMS

Index files
/system
catalog /data
blocks

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

DBMS Client-Server
Architecture

Will be covered in the Tutorial

Ref: Sec. 2.5 of the Textbook

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

Classification of DBMS

Will be covered in the Tutorial

Ref: Sec. 2.6 of the Textbook

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus

 Summary
✓ What is Data, Database, and DBMS
✓ Importance of DBMS
✓ Advantages of DBMS over traditional file systems
✓ Users of DBS
✓ What is a data model
✓ What is abstraction
✓ What is three schema architecture of a DBMS
✓ What is data independence
✓ Components of a DBMS
✓ DBMS Client server Architectures (Tut-2)
✓ Classification of DBMS (Tut-2)

Prof.R Gururaj Database Systems BITS Pilani, Hyderabad Campus