Today Goals

8/14/2019 Today Goals

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What is a Database?What is a Database?

File and TypesFile and Types

Data Access MethodsData Access Methods

Database Management SystemDatabase Management System

Advantages / Disadvantages of DBMSAdvantages / Disadvantages of DBMS

Database Access TypesDatabase Access Types

Database ModelsDatabase Models

Features of DatabaseFeatures of Database

Institute of Space Technology

Today GoalsToday Goals


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DataData - simple facts about people, objects, and events,- simple facts about people, objects, and events,

etc.etc.

InformationInformation - Derived data from processing the facts- Derived data from processing the factsthat is useful to us.that is useful to us.

Whats the problem we are facing today?Whats the problem we are facing today?

Data exist everywhere, but they may not be useableData exist everywhere, but they may not be useable

or retrievable.or retrievable.

We need to know how to capture data, and how toWe need to know how to capture data, and how to

organize them into computer!!organize them into computer!!

Data v.s InformationData v.s Information



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Database is a collection of dataDatabase is a collection of data

data is known facts with implicit meaningdata is known facts with implicit meaning

database is logically organized collection of relateddatabase is logically organized collection of related

data designed, built and populated for a specificdata designed, built and populated for a specificpurpose.purpose.

Examples:Examp

les:

Student Information SystemStudent Information System

Library SystemLibrary System

Medical SystemMedical System

Etc.Etc.



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Type of dataType of data ContainsContains ExampleExample

DatabaseDatabase Several FilesSeveral Files PersonalPersonalDatabaseDatabase

FileFile SeveralSeveralRecordsRecords

Name1Name1

Name2Name2

RecordRecord Several FieldsSeveral Fields Aamir Habib,Aamir Habib,

IST, IslamabadIST, IslamabadHighway nearHighway nearToll Plaza, IsbToll Plaza, Isb

FieldField CharactersCharacters(bytes)(bytes)

First Name:First Name:AamirAamir

CharactersCharacters Bits (0,1)Bits (0,1) Letter SLetter S

1110 00101110 0010

Database Storage Hierarchy

Key Field: ID Number, Customer Account No, etc


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File And TypesFile And Types



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Files And TypesFiles And Types File is a collection of data or information that is treated as a unit by the computer.File is a collection of data or information that is treated as a unit by the computer.

File has aFile has a namename and anand an extensionextension

Two major type of Files:Two major type of Files:

Program Files containing Software instructionProgram Files containing Software instruction

Source FilesSource Files

Executable FilesExecutable Files

Data Files contain DataData Files contain Data

.txt.txt

.xls.xls .ppt.ppt

.mdb.mdb



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Files And TypesFiles And Types

Two Types of Data Files:Two Types of Data Files:

Master FileMaster File containing relatively containing relativelypermanent records that are updatedpermanent records that are updated

periodically e.g address file of studentsperiodically e.g address file of students

Transaction FileTransaction File temporary holding file temporary holding filethat holds all the changes to be made tothat holds all the changes to be made to

the master file: addition, deletions,the master file: addition, deletions,revisions e.g new names and address torevisions e.g new names and address tobe added.be added.



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Sequential AccessSequential Access data is stored and retrieved in a data is stored and retrieved in a

sequence. Like Tape Storage.sequence. Like Tape Storage.

Direct AccessDirect Access

data is stored and accessed directly. data is stored and accessed directly.

Data is accessed according to a unique identifier thatData is accessed according to a unique identifier that

maps on to the address of the record.maps on to the address of the record.

Like CD Player, Hard Disk, etc.Like CD Player, Hard Disk, etc.

Ideal for applications likeIdeal for applications like

Airline Reservation Systems,Airline Reservation Systems,

Computer based Telephone DirectoryComputer based Telephone Directory



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Database ManagementDatabase Management

SystemSystem



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Database ManagementDatabase Management

SystemSystem

Database Management System isDatabase Management System is

Collection of programs which support creation andCollection of programs which support creation and

maintenance of databasemaintenance of database

That set up and controls the structure of databaseThat set up and controls the structure of databaseand access the Dataand access the Data

Program that are used to define, construct, maintainProgram that are used to define, construct, maintain

and manipulate data in a database.and manipulate data in a database.

Examples:Examples:

Oracle , SQL Server, FoxPro, MS Access, etc.Oracle , SQL Server, FoxPro, MS Access, etc.



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Advantages of DBMSAdvantages of DBMS

Sharing a DataSharing a Data

Control of RedundancyControl of Redundancy

Data IntegrityData Integrity

Better Data SecurityBetter Data Security Backup and RecoveryBackup and Recovery

Multiple Views of DataMultiple Views of Data

Faster Application DevelopmentFaster Application Development



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Disadvantages of DBMSDisadvantages of DBMS

High Cost of DBMSHigh Cost of DBMS

High Cost of HardwareHigh Cost of Hardware

Higher Programming CostHigher Programming Cost

Skilled Manpower requiredSkilled Manpower required

Etc.Etc.



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Database Access TypesDatabase Access Types

Individual DBIndividual DB collection of integrated files used by collection of integrated files used by

one person.one person.

Multi User DBMulti User DB aa Shared DBShared DB is shared by users in an is shared by users in an

organization.organization.

Distributed DBDistributed DB collection of integrated files stored in collection of integrated files stored in

different computers. DNSdifferent computers. DNS

Public DBPublic DB

compilation of data available for all the users. compilation of data available for all the users.

e.g. PTCL directory available online.e.g. PTCL directory available online.



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Data Management InterfaceData Management Interface

ToolsTools

Creating tablesCreating tables

Viewing recordsViewing records Sorting recordsSorting records

Creating queriesCreating queries

Generating reportsGenerating reports


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Steps for Creating FieldsSteps for Creating Fields

Name the fieldName the field

Specify the field typeSpecify the field type

Specify the field sizeSpecify the field size


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Types of FieldsTypes of Fields

TextText

NumericNumeric

Date or timeDate or time LogicalLogical

BinaryBinary

CounterCounter MemoMemo


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A Database Model is a collection ofA Database Model is a collection of

concepts for describing data.concepts for describing data.

Hierarchical DatabaseHierarchical Database

Network DatabaseNetwork Database

Relational DatabaseRelational Database

Object Oriented DatabaseObject Oriented Database

AA Relational data model is the mostRelational data model is the most

widely used data model todaywidely used data model today



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Student

Name Address CNIC Course GPA

Course A Course B Course CFirst

Name

Last

Name

Middle

Name

Exam 2 Exam 3 Grade

Grade

Exam 1

Exam 2

GradeExamExam 1

Hierarchical Database

Tree Structure

representing a student

record


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Network Database


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Relational Databases


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Features of a DatabaseFeatures of a Database



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OO DatabaseOO Database Uses objectsUses objects

DataData

InstructionsInstructions

OO Database is a multimedia database where more type of dataOO Database is a multimedia database where more type of data

can be stored e.g. a student OO Databasecan be stored e.g. a student OO Database

DataData

PhotographPhotograph

Sound biteSound bite

Short piece of videoShort piece of video

GradesGrades

Personal dataPersonal data

OperationsOperations

Examples FastObjects, eXcelon, Objectware, GemstoneExamples FastObjects, eXcelon, Objectware, Gemstone

A hypertext database (web database) Cold FusionA hypertext database (web database) Cold Fusion

Object-Relational or enhanced-relational Oracle 8,9,10, DB2Object-Relational or enhanced-relational Oracle 8,9,10, DB2


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Features of a DatabaseFeatures of a Database Data dictionaryData dictionary describes files and fields of data describes files and fields of data

UtilitiesUtilities Programs that allow you to maintain the database by Programs that allow you to maintain the database by

creating, editing and deleting data, records and files.creating, editing and deleting data, records and files.

Report GeneratorReport Generator Program for producing a printed document from Program for producing a printed document from

the database.the database.

Access SecurityAccess Security Specifies user access privileges Specifies user access privileges

Data RecoveryData Recovery Enables contents of database to be recovered after Enables contents of database to be recovered after

system failure.system failure.

Mirroring : two copies in different locationsMirroring : two copies in different locations

Reprocessing: redoing the processing from a known past pointReprocessing: redoing the processing from a known past point

Roll forward: a variant on reprocessing-Forward Recovery-Roll forward: a variant on reprocessing-Forward Recovery-

transactions or not reentered.transactions or not reentered.

Rollback: Backward recovery- undo unwanted changesRollback: Backward recovery- undo unwanted changes


Today Goals

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