Introduction to Database

Learning Objectives
• Definition of database
• How modern database evolve from file systems
• Database approach
• The main function of a database management
system
• Components of database
• Level of data abstraction
• Database architecture
 Introduction
• Today the success of an organisation depends
on its ability to acquire accurate and timely
data about its operations,to manage this data
effectively, and to use it to analyse and guide
it activities.
 Introduction
What is a database?
• A database is a collection of information
organized to provide efficient retrieval. The
collected information could be in any number
of formats (text, graphic, audio, video,
statistical, combinations).
 Class Quiz
• Discuss/mention any database system that
you interact with since last week?
 WhatIntroduction
is a database ??
• A database is a collection of information that is
organized so that it can be easily accessed,
managed and updated.
• Data is organized into rows, columns and tables,
and it is indexed to make it easier to find relevant
information. Data gets updated, expanded and
deleted as new information is added. Databases
process workloads to create and update
themselves, querying the data they contain and
running applications against it.
 Introduction
a database ??

• Computer databases typically

contain aggregations of data
records or files, such as sales
transactions, product catalogs
and inventories, and
customer profiles.
• Typically, a database manager
provides users with the ability
to control read/write access,
specify report generation and
analyze usage.
 Database: Historical roots
• Understanding what database is, will help in
classify what its is not.
• History will help in understanding data access
limitations that databases attempt to
overcome.
• A brief explanation of the evolution of file
system data processing can be helpful in
understanding the data access limitations that
databases attempt to overcome.
 Manual file system
• Keep track of data
• Used tagged file folders in a
filling cabinet
• Organized according to expected
use
e.g. file per customer
• Easy to create, but hard to
 locate data
 aggregate/ summarize data
 Disadvantage/Drawbacks
Here are some disadvantages of manual document
filing processes.
• Takes Up a Lot of Space. The biggest downfall
to manual document filing is the amount of space
it can take up
• Prone to Damage and Being Misplaced
• Hard to Make Changes
• Access Time
• Lack of Security
• Higher Cost
 Traditional file processing systems
• This was an early attempt to computerize the
manual filing system that we are all familiar
with.
• A file system is a method for storing and
organizing computer files and the data they
contain to make it easy to find and access
them.
Traditional file processing systems vs
Database approach
 Disadvantages of file processing systems

• Duplication of data
• Limited data sharing
• Lengthy development time
• Excessive program maintenance
• Program-data dependence
 Database approach
• The database approach emphasize the
integration and sharing of data through-out
the organisation
• Organisations expect to gain certain
advantages through the use of this approach
which is primarily bases of relational model
and data warehouses.
Advantages of Database approach

• Improve data consistancy

• Improve data sharing
• Increased productivity of application
development
• Reduce program maintence
• Improve decision support
• Improve data accessibility and responsiveness
 Cost and Risk of Database approach

• New, specialized personnel-need to hire or train individuals to design

and maintain

• Installation and Management cost and

complexity- initial cost is high
• Conversion cost
• Need for explicit backup and recovery
• Organisation conflict
 DBMS
• A DBMS makes it possible for end users to create,
read, update and delete data in a database. The
DBMS essentially serves as an interface between
the database and end users or application
programs , ensuring that data is consistently
organized and remains easily accessible.
• Database Management System is a software
system that is used to create, maintain and
provide controlled access to user databases.
Component of Database System
 Component of a Database Includes
• User: – Users are the one who really uses the
database. Users can be administrator, developer or
the end users.
• DBMS: – This is the software helps the user to
interact with the database. It allows the users to
insert, delete, update or retrieve the data. All these
operations are handled by query languages like
MySQL, Oracle etc.
• Database Application: – It the application program
which helps the users to interact with the database
by means of query languages. Database application
will not have any idea about the underlying DBMS.
 Database Applications:

• Banking: all transactions

• Airlines: reservation, grades
• Sales: customers, products, purchases
• Human resources: employee records, salaries,
tax deductions
Database Applications:

MTC now has 2 million active subscribers,.

Collection and analysis of customer

purchasing for shop floor optimization (data
warehouse)

Storage and retrieval of multimedia data

(pictures, video, sound

Use to store student records

IUM ITS iEnabler
 Data Abstraction in DBMS

• Database systems are made-up of complex

data structures.
• To ease the user interaction with database,
the developers hide internal irrelevant details
from users.
• This process of hiding irrelevant details from
user is called data abstraction.
Data Abstraction in DBMS
 We have three levels of abstraction:

1. Physical level:
• This is the lowest level of data abstraction.
• It describes how data is actually stored in
database.
• You can get the complex data structure details
at this level.
 We have three levels of abstraction

2. Logical level
• This is the middle level of 3-level data
abstraction architecture. It describes what data
is stored in database.

3. View level
• Highest level of data abstraction. This level
describes the user interaction with database
system.
 We have three levels of abstraction

Example: Let’s say we are storing customer

information in a customer table.

At physical level these records can be described

as blocks of storage (bytes, gigabytes, terabytes
etc.) in memory. These details are often hidden
from the programmers.
 We have three levels of abstraction
• At the logical level these records can be
described as fields and attributes along with
their data types, their relationship among
each other can be logically implemented.
• The programmers generally work at this level
because they are aware of such things about
database systems.
 We have three levels of abstraction
• At view level, user just interact with system
with the help of GUI and enter the details at
the screen, they are not aware of how the
data is stored and what data is stored; such
details are hidden from them.
 Goal of 3 level/schema of Database

Here, are some Objectives of using Three schema

Architecture:
• Every user should be able to access the same data but
able to see a customized view of the data.
• The user need not to deal directly with physical
database storage detail.
• The DBA should be able to change the database storage
structure without disturbing the user's views
• The internal structure of the database should remain
unaffected when changes made to the physical aspects
of storage.
 What is Database Architecture?

• DBMS architecture helps in design,

development, implementation, and
maintenance of a database.
• A database stores critical information for a
business. Selecting the correct Database
Architecture helps in quick and secure access
to this data.
 1 tier Architecture

• The simplest of Database

Architecture are 1 tier where the
Client, Server, and Database all
reside on the same machine.
• Anytime you install a DB in your
system and access it to practise SQL
queries it is 1 tier architecture. But
such architecture is rarely used in
production.
 2 tier Architecture

• A two-tier architecture is a database

architecture where
• Presentation layer runs on a client (PC, Mobile,
Tablet, etc)
• Data is stored on a Server.
• An application interface which is called ODBC
(Open Database Connectivity) an API which
allows the client-side program to call the
DBMS. Today most of the DBMS offers ODBC
drivers for their DBMS. 2 tier architecture
provides added security to the DBMS as it is
not exposed to the end user directly.
• Example of Two-tier Architecture is a Contact
Management System created using MS-
Access.
 3-tier Architecture

• 3-tier schema is an extension

of the 2-tier architecture. 3-
tier architecture has
following layers
• Presentation layer (your PC,
Tablet, Mobile, etc.)
• Application layer (server)
• Database Server
This DBMS architecture contains an Application layer
between the user and the DBMS, which is responsible for
communicating the user's request to the DBMS system and
send the response from the DBMS to the user.
 The goal of Three-teir architecture is:
• To separate the user applications and physical
database
• Proposed to support DBMS characteristics
• Program-data independence
• Support of multiple views of the data
 VARIOUS COMMON OF DBMS
• Oracle
• Microsoft Access
• SQL Server
• Sybase
• FoxPro
• MySQL