lect 12 database system

8/8/2019 Lect 12 Database System

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1

Fundamentals of

Database Systems


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What is a Database?

A database is any organized collection of data.Some examples of databases you mayencounter in your daily life are:

a telephone book T.V. Guide

airline reservation system

motor vehicle registration records

papers in your filing cabinet

files on your computer hard drive.


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What is a Database?

A collection of related facts

Filing CabinetFiling CabinetHard disk full of dataHard disk full of data

DiaryDiary

Library


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Basics of Database

A Database consists of four elements:

Data: Data is nothing but the facts

Relationship : It represents the correspondencebetween the various data elements

Constraints : Constraints are the predicates thatdefine correct database state

Schema : It describes the organization of data


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Relationship Types

One-to-one (1:1)

One-to-many (1:M)

Many-to-many (M:M)


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Table

A table is the primary unit of physical storage

for data in a database.1

Usually a database contains more than one

table.

1) Stephens, R.K. and Plew. R.R., 2001. Database Design. SAMS, Indianapolis , IN.


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Table


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Field (Column)

a field

Customers


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Record (Row)

a record

Customers


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Why a Database System

Redundancy Can be controlled

Inconsistency can be avoided

Data can be shared Standards can be enforced

Security restrictions can be applied

Integrity can be maintained


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What is a DBMS?

DBMS - DataBase Management System

Multiple Billion dollar market for DBMS products and

services !

A software system for defining, constructing and

manipulating databases for various applications

DBMS may be general purpose (business

applications) or special purpose (biologicaldatabases, geographic information, ...)


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What is a Database System?

ApplicationApplication Programs/Queries

Software to Process

Queries/Programs

Software to Access

Stored Data

DATABASE SYSTEMDATABASE SYSTEM

DBMS SOFTWARE

Users/Programmers

Stored Database

Definition

(Meta-Data)

Stored

Database

DBMSDBMS

++DatabaseDatabase

==

Database SystemDatabase System


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Database System Components

T

he Stored Database A collection of related facts The DBMS The software that defines, constructs and

manipulates a database

The Applications The programs (in specific languages) that

manipulate the database The Users

People who use the database system, throughthe DBMS interface or through applicationprograms


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Database Users

Database administrators: responsible for authorizingaccess to the database, for coordinating andmonitoring its use, acquiring software, and hardwareresources, controlling its use and monitoring

efficiency of operations. Database Designers: responsible to define the

content, the structure, the constraints, and functionsor transactions against the database. They must

communicate with the end-users and understandtheir needs.

End-users: they use the data for queries, reports andsome of them actually update the database content.


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Levels of Abstraction

Views describe howusers see the data.

Conceptual schemadefines logicalstructure

Physical schemadescribes the files andindexes used.

Physical Schema

Conceptual Schema

View 1 View 2 View3

DB

Users


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Functions of DBMS

Transaction Management

Concurrency Control

Recovery Management Security Management

Language Interface

Storage Management Data Catalog Management


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Type of Database

Operational Database : It stores detailed dataneeded to support the business process andoperations of the company

Distributed Database : Many organizationsreplicate and distribute copies or part ofdatabase to network server

External Database : Database which is not

owned by the company

Hypermedia Database : Advanced Databasewhich uses hyper linking


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What is Data Warehousing?

Data warehousing is subject-oriented, integrated,time-variant, and non-volatile collection of data insupport of managements decision-making process.

a data warehouse is data management and dataanalysis tool

Data webhouse is a distributed data warehouse thatis implement over the web with no central datarepository

goal: is to integrate enterprise wide corporate datainto a single reository from which users can easilyrun queries


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Components of Data Warehouse

Summarized Data

Operational System ofRecords

Integration/Transformation Program Current Detail

Meta Data

Archives


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Data Warehouse Organization

I/T P Current Detail ArchiveOSR

Meta DataL S/D

H

S/D


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The benefits of data warehousing

The potential benefits of data warehousing

are high returns on investment..

substantial competitive advantage.. increased productivity of corporate decision-

makers..

lect 12 database system

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