2. Introduction to DBMS

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Introduction to Databaseana emen ys em


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ObjectivesObjectives Define termsDefine terms

Name limitations of conventional file processingName limitations of conventional file processing Explain advantages of databasesExplain advantages of databases

Identify costs and risks of databasesIdentify costs and risks of databases

List components of database environmentList components of database environment en y ca e or es o a a ase app ca onsen y ca e or es o a a ase app ca ons

Describe database system development life cycleDescribe database system development life cycle

Explain roles of individualsExplain roles of individuals

Ex lain the threeEx lain the three--schema architecture for databasesschema architecture for databases


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DefinitionsDefinitions Data ase:Data ase:

Organized collection of logically related dataOrganized collection of logically related data

Stored representations of meaningful objects andStored representations of meaningful objects and

eventsevents

Structured:Structured:

Numbers, text, datesNumbers, text, dates

Images, video, documentsImages, video, documents

Information:Information:

Data processed to increase knowledge in the personData processed to increase knowledge in the personusing the datausing the data

e a a a:e a a a:

Data that describes the properties and context of userData that describes the properties and context of userdatadata


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Context helps users understand data


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Summarized data

Graphical displays turn data into usefulinformation that managers can use for

decision making and interpretation


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Descriptions of the properties or characteristics of thedata, including data types, field sizes, allowable


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Disadvantages of File ProcessingDisadvantages of File Processing

ProgramProgram--Data DependenceData Dependence All programs maintain metadata for each file they useAll programs maintain metadata for each file they use

Duplication of DataDuplication of Data Different systems/programs have separate copies of the same dataDifferent systems/programs have separate copies of the same data

No centralized control of dataNo centralized control of data

Programmers must design their own file formatsProgrammers must design their own file formats

Excessive Pro ram MaintenanceExcessive Pro ram Maintenance 80% of information systems budget80% of information systems budget


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ro ems w a a epen encyro ems w a a epen ency Each application programmer must maintainEach application programmer must maintain

his/her own datahis/her own data Each application program needs to includeEach application program needs to include

Each application program must have its ownEach application program must have its own

updating, and deleting dataupdating, and deleting data

Lack of coordination and central controlLack of coordination and central control

NonNon--standard file formatsstandard file formats


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Problems with Data RedundancyProblems with Data Redundancy

Waste of space to have duplicate dataWaste of space to have duplicate data

auses more ma n enance ea ac esauses more ma n enance ea ac es

The bi est roblem:The bi est roblem: Data changes in one file could causeData changes in one file could cause

Compromises inCompromises in dat a int egr i t ydat a int egr i t y


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SOLUTION:SOLUTION:

e pproace pproac

Data is managed by a controllingData is managed by a controllingagenagen

Stored in a standardized convenientStored in a standardized convenient

formform


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A software system that is used to create, maintain, and provide

controlled access to user databases

Order FilingSystem

Invoicing

System DBMS

Central database

Payroll

,order, inventory,

pricing, andcustomer data

manages a a resources e an opera ng sys em manages ar wareresources


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vantages o t e ata asevantages o t e ata ase

A roachA roach ProgramProgram--data independencedata independence Planned data redundancyPlanned data redundancy

Improved data consistencyImproved data consistency

Improved data sharingImproved data sharing

Enforcement of standardsEnforcement of standards

Improved data accessibility and responsivenessImproved data accessibility and responsiveness

Reduced program maintenanceReduced program maintenance

Improved decision supportImproved decision support


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Costs and Risks of the DatabaseCosts and Risks of the Database

,,

Installation and management cost andInstallation and management cost and

Conversion costsConversion costs

The change managementThe change management


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Elements of the DatabaseElements of the Database

Data modelsData models Graphical system capturing nature and relationship of dataGraphical system capturing nature and relationship of data

the organizationthe organization

Project Data ModelProject Data Model more detailed view, matching datamore detailed view, matching datastructure in database or data warehousestructure in database or data warehouse

EntitiesEntities Noun form describing a person, place, object, event, or conceptNoun form describing a person, place, object, event, or concept

Composed of attributesComposed of attributes

RelationshipsRelationships Between entitiesBetween entities

Usually oneUsually one--toto--many (1:M) or manymany (1:M) or many--toto--many (M:N)many (M:N)

Relational DatabasesRelational Databases

Database technology involving tables (relations) representingDatabase technology involving tables (relations) representingentities and primary/foreign keys representing relationshipsentities and primary/foreign keys representing relationships


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Segment of an enterprise data model

-


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One customer

may place many

orders, but each

order is placed by

a sin le customer

One-to-many

relationshi


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One order has

many or er nes;

each order line is

associated with a

single order

One-to-many

relationship


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One product can

order lines, each

order line refers

to a single

product

ne- o-many

relationship


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,

order involvesmany products

and one product is

involved in many

orders

Many-to-many


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Components of the Database Environment


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omponents o t eomponents o t eDatabase EnvironmentDatabase Environment

CASE ToolsCASE Toolscomputercomputer--aided software engineeringaided software engineering RepositoryRepositorycentralized storehouse of metadatacentralized storehouse of metadata

Database Management System (DBMS)Database Management System (DBMS) software forsoftware formanaging the databasemanaging the database

Application ProgramsApplication Programssoftware using the datasoftware using the data

User InterfaceUser Interfacetext and graphical displays to userstext and graphical displays to users

a a a a ase m n s ra orsa a a a ase m n s ra orspersonne respons epersonne respons efor maintaining the databasefor maintaining the database

System DevelopersSystem Developerspersonnel responsible forpersonnel responsible fores gn ng a a ases an so warees gn ng a a ases an so ware

End UsersEnd Userspeople who use the applications andpeople who use the applications anddatabasesdatabases


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The Range of Database ApplicationsThe Range of Database Applications

Personal databasesPersonal databases

TwoTwo--tier Client/Server databasestier Client/Server databases

Enterprise applicationsEnterprise applications

Data warehousing implementationsData warehousing implementations


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Two-tier database with local


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Three-tiered client/server database architecture


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Enterprise Database ApplicationsEnterprise Database Applications

Enter rise Resource Plannin ERPEnter rise Resource Plannin ERP

Integrate all enterprise functionsIntegrate all enterprise functions

(manufacturing, finance, sales, marketing,(manufacturing, finance, sales, marketing,inventory, accounting, human resources)inventory, accounting, human resources)

Data WarehouseData Warehouse

Integrated decision support system derived fromIntegrated decision support system derived fromvarious operational databasesvarious operational databases


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Evolution of database technologies


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wo pproac es to ata ase anwo pproac es to ata ase anIS Develo mentIS Develo ment

SDLCSDLC System Development Life CycleSystem Development Life Cycle

Detailed, wellDetailed, well--planned development processplanned development process

TimeTime--consuming, but comprehensiveconsuming, but comprehensive

PrototypingPrototyping Rapid application development (RAD)Rapid application development (RAD)

Cursory attempt at conceptual data modelingCursory attempt at conceptual data modeling Define database during development of initialDefine database during development of initial

Repeat implementation and maintenance activitiesRepeat implementation and maintenance activitieswith new prototype versionswith new prototype versions


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Systems Development Life CycleSystems Development Life Cycle

Planning

Logical Design

Physical Design

Implementation


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(cont.)(cont.)Pur ose reliminar understandin

Analysis

Deliverablerequest for study

Logical Design

Physical Design

Database activit

Maintenance

enterprise modeling andearly conceptual data

modeling


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(cont.)(cont.)Purposethorough requirements analysis and

AnalysisAnalysis

structur ng

Deliverablefunctional system specifications

Logical Design

Physical Design

Database activit thorou h

Maintenance

and integrated conceptualdata modeling


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(cont.)(cont.)Purposeinformation requirements elicitation

Analysis

Deliverabledetailed design specifications

Logical DesignLogical Design

Physical Design

Database activit

Maintenance

logical database design(transactions, forms,

displays, views, data

integrity and security)


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(cont.)(cont.)Purposedevelop technology and

organizational specifications

AnalysisDeliverableprogram/datastructures, technology purchases,

Logical Design

organization redesigns

Physical DesignPhysical Design

Database activit

Maintenance

physical database design (definedatabase to DBMS, physical

data organization, database

processing programs)


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(cont.)(cont.)Purposeprogramming, testing,

Analysis

, ,

Deliverableoperational programs,

Logical Design

Physical Design

Database activity

Maintenance

a a ase mp emen a on,

including coded programs,

documentation,


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(cont.)(cont.)Purposemonitor, repair, enhance

AnalysisDeliverableperiodic audits

Logical Design

Physical Design

Database activity

MaintenanceMaintenance

a a ase ma n enance,

performance analysis

and tuning, error


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Prototyping Database MethodologyPrototyping Database Methodology

P t t i D t b M th d lP t t i D t b M th d l


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..

P t t i D t b M th d lP t t i D t b M th d l


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..



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cont.cont.



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..


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Managing ProjectsManaging Projects Pro ectPro ecta lanned undertakin of relateda lanned undertakin of related

activities to reach an objective that has aactivities to reach an objective that has abeginning and an endbeginning and an end

Validation of satisfactory progressValidation of satisfactory progress

Ste back from detail to overall viewSte back from detail to overall view Renew commitment of stakeholdersRenew commitment of stakeholders

Incremental commitmentIncremental commitmentreview of systemsreview of systems

eve opmen pro ec a er eaceve opmen pro ec a er eacdevelopment phase withdevelopment phase with rejustificationrejustification afteraftereach haseeach hase


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anag ng ro ec s: eop eanag ng ro ec s: eop eInvolvedInvolved Business analystsBusiness analysts

Systems analystsSystems analysts

Database analysts and data modelersDatabase analysts and data modelers

UsersUsers ProgrammersProgrammers

Database architectsDatabase architects

Data administratorsData administrators

Other technical expertsOther technical experts


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Terminology

Relation

Attribute


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Database SchemaDatabase Schema External SchemaExternal Schema User ViewsUser Views

Subsets of Conceptual SchemaSubsets of Conceptual Schema

an e e erm ne rom us nessan e e erm ne rom us ness-- unc on a aunc on a aentity matricesentity matrices

DBA determines schema for different usersDBA determines schema for different users Conceptual SchemaConceptual Schema

Internal SchemaInternal Schema

Three-schema architecture


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Different people

have different

databasethese

are the external

The internal

schema is the

underlying

implementation


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Enterprise Data ModelEnterprise Data Model

First step in database developmentFirst step in database development S ecifies sco e and eneral contentS ecifies sco e and eneral content

Overall picture of organizational data at highOverall picture of organizational data at high

level of abstractionlevel of abstraction EntityEntity--relationship diagramrelationship diagram

Descri tions of entit t esDescri tions of entit t es

Relationships between entitiesRelationships between entities

Documents

2. Introduction to DBMS