cs371 lecture 01

8/8/2019 Cs371 Lecture 01

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File Systems and Databases

Lecture 1

8/8/2019 Cs371 Lecture 01


Files and Databases

File: A collection of records or documentsdealing with one organization, person, area orsubject (Rowley)

± Manual (paper) files

± Computer files

Database: A collection of similar records with

relationships between the records (Rowley) ± Bibliographic, statistical, business data, images,

etc.

8/8/2019 Cs371 Lecture 01


Introducing the DatabaseIntroducing the Database

Major Database Concepts

± Data and information

Data - Raw facts

Information - Processed data

± Data management & Data Administrator

± Database & Database Administrator

± Metadata

± Database management system (DBMS)

8/8/2019 Cs371 Lecture 01


8/8/2019 Cs371 Lecture 01


Contents of the CUSTOMER File

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8/8/2019 Cs371 Lecture 01


Table 1.1 Basic File Terminologyata ³Raw´ facts that have little meaning unless they have beenorganized in some logical manner. The smallest piece of datathat can be ³recognized´ by the computer is a singlecharacter, such as the letter A, the number 5, or somesymbol such as; µ ? > * +. A single character requires onebyte of computer storage.

Fiel A character or group of characters (alphabetic or numeric)that has a specific meaning. A field might define a telephonenumbers, a birth date, a customer name, a year-to-date(YTD) sales value, and so on.

ecor A logically connected set of one or more fields that describesa person, place, or thing. For example, the fields that

comprise a record for a customer named J. D. Rudd mightconsist of J. D. Rudd¶s name, address, phone number, dateof birth, credit limit, unpaid balance, and so on.

File A collection of related records. For example, a file mightcontain data about ROBCOR Company¶s vendors; or, a filemight contain the records for the students currently enrolledat Gigantic University.

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Limitation of Computerized File-basedApproach

Separation and Isolation of data

Eac applicati ai tai s its s t f ata.

s rs f applicati ay awar f pot tially

s f l ata l y ot r applications.

Duplication of data (data redundancy)

Same ata is el y iff er ent files.

Limited Data Sharing

No centr alized contr ol of data

Lengthy Development Times

Pr ogr ammersmust design t eir own file f or mats

Excessive Pr ogram Maintenance

80% of inf or mation systems udget

8/8/2019 Cs371 Lecture 01


Limitation of File-basedApproach

Accessibility

Data is stor ed using pr ogr ams t at ar e written in

diff er ent languages and f or mat

annot easily access ot er files due to incompati le file

f or mat.

No contr ol over access and manipulation of data eyond

t at imposed y application pr ogr ams.

Hard Coded Queries (Data dependence)

ile str uctur e and all definition of data ar e defined in t e

application pr ogr am code.

ny new r equir ement needs a new pr ogr am.

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Database Processing

System

SOLUTION:SOLUTION:

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Data Administrator

Data Administrator is responsible for the

entire data of an organization. He normally

develops the overall functional requirements

for the databases being used in offices.

8/8/2019 Cs371 Lecture 01


Database Administrator

The Database Administrator is responsible for

the design, implementation, operations,

management and maintenance of the

database.

8/8/2019 Cs371 Lecture 01


Database Management System (DBMS)

A collection of pr ograms t at enables users to define, cr eate

and maintain and contr ol access to t e database.

ener al-pur pose softwar e system t at f acilitates t e pr ocessesof def ining, constructing and manipulating databases f or

various applications.

Def ining - specif ying data types, str uctur es, constr aints.Constructing - storing of data

Manipulation - quer ying, updating and r eporting.

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Popular DBMS In The Market

Sybase SQL Anywhere

Informix Dynamic Server

Borland Interbase

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8/8/2019 Cs371 Lecture 01


The DBMS Manages the Interaction

Between the End User and the Database

8/8/2019 Cs371 Lecture 01


Database SystemsDatabase Systems

The Database System Components

± Hardware

Computer

Peripherals

± Software

Operating systems software

DBMS software

Applications programs and utilities software

8/8/2019 Cs371 Lecture 01


Database SystemsDatabase Systems

The Database System Components

± People

Systems administrators

Database administrators (DBAs)

Database designers

Systems analysts and programmers

End users

± Procedures

I

nstructions and rules that govern the design and use of the databasesystem

± Data

Collection of facts stored in the database

8/8/2019 Cs371 Lecture 01


Database Systems

Types of Database Systems

± Location

Centralized

Distributed

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8/8/2019 Cs371 Lecture 01


Data Independence

Logical Data Independence:

The capacity to change the conceptual schema without having to change

the external schemas and their associated application programs.

Physical Data Independence:

The capacity to change the internal schema without having to change theconceptual schema. For example, the internal schema may be changed

when certain file structures are reorganized or new indexes are created to

improve database performance

cs371 lecture 01

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