(數(shù)據(jù)庫原理課件)Chapter2-Database-System-Development-Life

DatabaseDesign.SchoolofsoftwareChapter2DatabaseSystemDevelopmentLifecycle何婧hejing@PartIDatabaseSystemDesignDatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareObjectivesdatabasesystemdevelopmentlifecycle2SoftwareCrisis1DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.1SoftwareCrisis(軟件危機(jī))Softwarecrisiswasatermusedintheearlydaysofcomputingscienceforthedifficultyofwritingusefulandefficientcomputerprogramsintherequiredtime.Themajorcauseofthesoftwarecrisisisthatthemachineshavebecomeseveralordersofmagnitudemorepowerful!Toputitquitebluntly:aslongastherewerenomachines,programmingwasnoproblematall;whenwehadafewweakcomputers,programmingbecameamildproblem,andnowwehavegiganticcomputers,programminghasbecomeanequallygiganticproblem.—

EdsgerDijkstra,

TheHumbleProgrammer(EWD340),

CommunicationsoftheACM,1972(1930-2002)DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.1SoftwareCrisis(軟件危機(jī))IBMOS/3601961-1964Morethan2000engineers5000person-yearsMorethan$500millionFrederickBrooks(1931-)A.M.TuringAward,AssociationforComputingMachinery(1999)TheMythicalMan-Month:EssaysonSoftwareEngineering（人月神話：軟件項(xiàng)目管理之道）DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.2StagesofdatabasesystemdevelopmentlifecycleDatabaseplanningSystemdefinitionRequirementscollectionandanalysisDatabasedesignDBMSselection(optional)DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.3StagesofdatabasesystemdevelopmentlifecycleApplicationdesignPrototyping(optional)ImplementationDataconversionandloadingTestingOperationalmaintenance.DatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareStagesofthedatabasesystemdevelopmentlifecycleDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware數(shù)據(jù)庫應(yīng)用開發(fā)周期各個階段采集的數(shù)據(jù)和產(chǎn)生的文檔示例開發(fā)階段捕獲的數(shù)據(jù)示例產(chǎn)生的文檔示例1數(shù)據(jù)庫規(guī)劃數(shù)據(jù)庫工程的目標(biāo)和目的任務(wù)描述和數(shù)據(jù)庫系統(tǒng)目的2系統(tǒng)定義主要用戶視圖描述（包括工作角色/或者業(yè)務(wù)應(yīng)用領(lǐng)域）數(shù)據(jù)庫系統(tǒng)的邊界和范圍定義，用戶視圖定義3需求收集和分析用戶視圖的要求，系統(tǒng)說明，包括性能和安全性要求用戶和系統(tǒng)的需求說明書4數(shù)據(jù)庫設(shè)計用戶對邏輯數(shù)據(jù)庫設(shè)計的反饋和對DBMS的要求邏輯數(shù)據(jù)庫設(shè)計（包括ER模型、數(shù)據(jù)字典、表），物理數(shù)據(jù)庫設(shè)計5應(yīng)用程序設(shè)計用戶對界面設(shè)計的反饋應(yīng)用程序設(shè)計DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware數(shù)據(jù)庫應(yīng)用開發(fā)周期各個階段采集的數(shù)據(jù)和產(chǎn)生的文檔示例開發(fā)階段捕獲的數(shù)據(jù)示例產(chǎn)生的文檔示例6DBMS的選擇目標(biāo)DBMS提供的功能DBMS評估和推薦7構(gòu)建原型用戶對原型的反映修改了的用戶需求和系統(tǒng)說明書8實(shí)現(xiàn)目標(biāo)DBMS提供的功能9數(shù)據(jù)轉(zhuǎn)換和加載當(dāng)前的數(shù)據(jù)格式，目標(biāo)DBMS的數(shù)據(jù)導(dǎo)入能力10測試測試結(jié)果測試方法、測試結(jié)果的分析11操作維護(hù)性能測試結(jié)果，新的系統(tǒng)需求用戶手冊、性能結(jié)果分析、修改的用戶需求與系統(tǒng)說明書DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.Databaseplanning

Managementactivitiesthatallowstagesofdatabasesystemdevelopmentlifecycletoberealizedasefficientlyandeffectivelyaspossible.ShouldbeintegratedwithoverallISstrategyoftheorganization.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningMissionstatement

(任務(wù)陳述)forthedatabaseprojectdefinesmajoraimsofdatabasesystem.Missionstatementhelpsclarifypurposeofthedatabaseprojectandprovidesclearerpathtowardstheefficientandeffectivecreationofrequireddatabasesystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningOncemissionstatementisdefined,missionobjectives

（任務(wù)目標(biāo)）aredefined.Eachobjectiveshouldidentifyaparticulartaskthatthedatabasemustsupport.Shouldalsoincludeadditionalinformationthatspecifiestheworktobedone,theresourceswithwhichtodoit,andthemoneytopayforitall.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningDatabaseplanningmayalsoincludedevelopmentofstandardsthatgovern:howdatawillbecollected,howtheformatshouldbespecified,whatnecessarydocumentationwillbeneeded,howdesignandimplementationshouldproceed.CaseDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.Systemdefinition

Describesscopeandboundariesofdatabasesystem,includingitsmajoruserviews.

Describeshowdatabasesystemwillinterfacewithotherpartsoftheorganization’sinformationsystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionBoundaryfordatabasesystemofStayHomeDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionBoundaryfordatabasesystemofStayHomeDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.Systemdefinition

Userview

defineswhatisrequiredofadatabasesystemfromtheperspectiveof:aparticularjob(suchasManagerorSupervisor)orbusinessapplicationarea(suchasmarketing,personnel,orstockcontrol).Databasesystemmayhaveoneormoreuserviews.

DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionDatabasesystemwithmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.Requirementscollectionandanalysis

Processofcollectingandanalyzinginformationabouttheorganizationtobesupportedbythedatabasesystem,andusingthisinformationtoidentifytherequirementsforthenewsystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.Requirementscollectionandanalysis231centralizedapproachviewintegrationapproach;combinationofbothapproaches.Threemainapproaches:DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisCentralizedapproach

Requirementsforeachuserviewaremergedintoasinglesetofrequirementsforthenewdatabasesystem.Adatamodelrepresentingalluserviewsiscreatedduringthedatabasedesignstage.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisCentralizedapproachtomanagingmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisViewintegrationapproachRequirementsforeachuserviewremainasseparatelists.Datamodelsrepresentingeachuserviewarecreatedandthenmergedduringthedatabasedesignstage.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisViewintegrationapproachtomanagingmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareStayHomeuserviewsanddataDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware*4.DatabasedesignProcessofcreatingadesignthatwillsupporttheorganization’smissionstatementandobjectivesfortherequireddatabasesystem.Twomainphasesofdatabasedesign:LogicaldatabasedesignPhysicaldatabasedesign.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware*4.3.4DatabasedesignLogicaldatabasedesignidentifiestheimportantobjectsthatneedtoberepresentedinthedatabaseandtherelationshipsbetweentheseobjects.

Physicaldatabasedesigndescribeshowthelogicaldesignistobephysicallyimplemented(astables)inthetargetDBMS.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware5.DBMSselection(Optional)

SelectionofanappropriateDBMStosupportthedatabasesystem.Undertakenatanytimepriortologicaldesignprovidedsufficientinformationisavailableregardingsystemrequirements.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware5.DBMSselection(Optional)

DB-Engines2015年2月數(shù)據(jù)庫排名DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.Applicationdesign

Designofuserinterfaceandapplicationprogramsthatuseandprocessthedatabase.Databaseandapplicationdesignareparallelactivities.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.Applicationdesign

Transactionisanaction,orseriesofactions,carriedoutbyasingleuserorapplicationprogramthataccessesorchangescontentofthedatabase.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.ApplicationdesignThreemaintypesoftransactions:retrievaltransactionsupdatetransactionsmixedtransactionsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.ApplicationdesignGuidelinesforform/reportdesignDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware7.Prototyping(Optional)

Buildingworkingmodelofadatabasesystem.Purposetoidentifyfeaturesofasystemthatworkwell,orareinadequate;tosuggestimprovementsorevennewfeatures;toclarifytheusers’requirements;toevaluatefeasibilityofaparticularsystemdesign.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware7.Prototyping(Optional)RequirementsprototypingdeterminestherequirementsofaproposeddatabasesystemandthentheprototypeisdiscardedprototypingstrategiesEvolutionaryprototypingisusedforthesamepurposes,buttheprototypeisnotdiscardedandwithfurtherdevelopmentbecomestheworkingdatabasesystemDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware8.ImplementationPhysicalrealizationofthedatabaseandapplicationdesigns.UseDDLtocreatedatabaseschemasandemptydatabasefiles.UseDDLtocreateuserviews.Use3GLor4GLtocreatetheapplicationprograms,whichincludesdatabasetransactions.UseDDLtoimplementsecurityandintegritycontrols.However,somemaybedefinedusingDBMSutilitiesoroperatingsystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware9.Dataconversionandloading

TmonforaDBMStohaveautilitythatloadsexistingfilesintothenewdatabase.Maybepossibletoconvertanduseapplicationprogramsfromtheoldsystemforusebythenewsystem.

DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware10.Testing

Processofrunningthedatabasesystemwiththeintentoffindingerrors.Usecarefullyplannedteststrategiesandrealisticdata.Testingcannotshowabsenceoffaults;itcanshowonlythatsoftwarefaultsarepresent.Demonstratesthatdatabaseandapplicationprogramsappeartobeworkingaccordingtorequirements.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware11.Operationalmaintenance

Processofmonitoringandmaintainingthedatabasesystemfollowinginstallationandinvolves:monitoringperformanceofsystem.Ifperformancefalls,mayrequiretuningorreorganizationofthedatabase.maintainingandupgradingdatabasesystem(whenrequired).incorporatingnewrequirementsintodatabasesystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftwareusers’requirementsspecification數(shù)據(jù)需求事務(wù)需求數(shù)據(jù)庫系統(tǒng)的系統(tǒng)說明初始數(shù)據(jù)庫大小數(shù)據(jù)庫增長速度記錄查找的類型和平均數(shù)量網(wǎng)絡(luò)和數(shù)據(jù)共享需求性能安全性備份和恢復(fù)用戶界面合法問題DatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareThankYou!hejing@DatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareChapter2DatabaseSystemDevelopmentLifecycle何婧hejing@PartIDatabaseSystemDesignDatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareObjectivesdatabasesystemdevelopmentlifecycle2SoftwareCrisis1DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.1SoftwareCrisis(軟件危機(jī))Softwarecrisiswasatermusedintheearlydaysofcomputingscienceforthedifficultyofwritingusefulandefficientcomputerprogramsintherequiredtime.Themajorcauseofthesoftwarecrisisisthatthemachineshavebecomeseveralordersofmagnitudemorepowerful!Toputitquitebluntly:aslongastherewerenomachines,programmingwasnoproblematall;whenwehadafewweakcomputers,programmingbecameamildproblem,andnowwehavegiganticcomputers,programminghasbecomeanequallygiganticproblem.—

EdsgerDijkstra,

TheHumbleProgrammer(EWD340),

CommunicationsoftheACM,1972(1930-2002)DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.1SoftwareCrisis(軟件危機(jī))IBMOS/3601961-1964Morethan2000engineers5000person-yearsMorethan$500millionFrederickBrooks(1931-)A.M.TuringAward,AssociationforComputingMachinery(1999)TheMythicalMan-Month:EssaysonSoftwareEngineering（人月神話：軟件項(xiàng)目管理之道）DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.2StagesofdatabasesystemdevelopmentlifecycleDatabaseplanningSystemdefinitionRequirementscollectionandanalysisDatabasedesignDBMSselection(optional)DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.3StagesofdatabasesystemdevelopmentlifecycleApplicationdesignPrototyping(optional)ImplementationDataconversionandloadingTestingOperationalmaintenance.DatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareStagesofthedatabasesystemdevelopmentlifecycleDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware數(shù)據(jù)庫應(yīng)用開發(fā)周期各個階段采集的數(shù)據(jù)和產(chǎn)生的文檔示例開發(fā)階段捕獲的數(shù)據(jù)示例產(chǎn)生的文檔示例1數(shù)據(jù)庫規(guī)劃數(shù)據(jù)庫工程的目標(biāo)和目的任務(wù)描述和數(shù)據(jù)庫系統(tǒng)目的2系統(tǒng)定義主要用戶視圖描述（包括工作角色/或者業(yè)務(wù)應(yīng)用領(lǐng)域）數(shù)據(jù)庫系統(tǒng)的邊界和范圍定義，用戶視圖定義3需求收集和分析用戶視圖的要求，系統(tǒng)說明，包括性能和安全性要求用戶和系統(tǒng)的需求說明書4數(shù)據(jù)庫設(shè)計用戶對邏輯數(shù)據(jù)庫設(shè)計的反饋和對DBMS的要求邏輯數(shù)據(jù)庫設(shè)計（包括ER模型、數(shù)據(jù)字典、表），物理數(shù)據(jù)庫設(shè)計5應(yīng)用程序設(shè)計用戶對界面設(shè)計的反饋應(yīng)用程序設(shè)計DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware數(shù)據(jù)庫應(yīng)用開發(fā)周期各個階段采集的數(shù)據(jù)和產(chǎn)生的文檔示例開發(fā)階段捕獲的數(shù)據(jù)示例產(chǎn)生的文檔示例6DBMS的選擇目標(biāo)DBMS提供的功能DBMS評估和推薦7構(gòu)建原型用戶對原型的反映修改了的用戶需求和系統(tǒng)說明書8實(shí)現(xiàn)目標(biāo)DBMS提供的功能9數(shù)據(jù)轉(zhuǎn)換和加載當(dāng)前的數(shù)據(jù)格式，目標(biāo)DBMS的數(shù)據(jù)導(dǎo)入能力10測試測試結(jié)果測試方法、測試結(jié)果的分析11操作維護(hù)性能測試結(jié)果，新的系統(tǒng)需求用戶手冊、性能結(jié)果分析、修改的用戶需求與系統(tǒng)說明書DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.Databaseplanning

Managementactivitiesthatallowstagesofdatabasesystemdevelopmentlifecycletoberealizedasefficientlyandeffectivelyaspossible.ShouldbeintegratedwithoverallISstrategyoftheorganization.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningMissionstatement

(任務(wù)陳述)forthedatabaseprojectdefinesmajoraimsofdatabasesystem.Missionstatementhelpsclarifypurposeofthedatabaseprojectandprovidesclearerpathtowardstheefficientandeffectivecreationofrequireddatabasesystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningOncemissionstatementisdefined,missionobjectives

（任務(wù)目標(biāo)）aredefined.Eachobjectiveshouldidentifyaparticulartaskthatthedatabasemustsupport.Shouldalsoincludeadditionalinformationthatspecifiestheworktobedone,theresourceswithwhichtodoit,andthemoneytopayforitall.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware1.DatabaseplanningDatabaseplanningmayalsoincludedevelopmentofstandardsthatgovern:howdatawillbecollected,howtheformatshouldbespecified,whatnecessarydocumentationwillbeneeded,howdesignandimplementationshouldproceed.CaseDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.Systemdefinition

Describesscopeandboundariesofdatabasesystem,includingitsmajoruserviews.

Describeshowdatabasesystemwillinterfacewithotherpartsoftheorganization’sinformationsystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionBoundaryfordatabasesystemofStayHomeDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionBoundaryfordatabasesystemofStayHomeDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.Systemdefinition

Userview

defineswhatisrequiredofadatabasesystemfromtheperspectiveof:aparticularjob(suchasManagerorSupervisor)orbusinessapplicationarea(suchasmarketing,personnel,orstockcontrol).Databasesystemmayhaveoneormoreuserviews.

DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionDatabasesystemwithmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware2.SystemdefinitionDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.Requirementscollectionandanalysis

Processofcollectingandanalyzinginformationabouttheorganizationtobesupportedbythedatabasesystem,andusingthisinformationtoidentifytherequirementsforthenewsystem.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.Requirementscollectionandanalysis231centralizedapproachviewintegrationapproach;combinationofbothapproaches.Threemainapproaches:DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisCentralizedapproach

Requirementsforeachuserviewaremergedintoasinglesetofrequirementsforthenewdatabasesystem.Adatamodelrepresentingalluserviewsiscreatedduringthedatabasedesignstage.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisCentralizedapproachtomanagingmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisViewintegrationapproachRequirementsforeachuserviewremainasseparatelists.Datamodelsrepresentingeachuserviewarecreatedandthenmergedduringthedatabasedesignstage.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware3.RequirementscollectionandanalysisViewintegrationapproachtomanagingmultipleuserviewsDatabaseDesign.SchoolofsoDatabaseDesign.SchoolofsoftwareStayHomeuserviewsanddataDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware*4.DatabasedesignProcessofcreatingadesignthatwillsupporttheorganization’smissionstatementandobjectivesfortherequireddatabasesystem.Twomainphasesofdatabasedesign:LogicaldatabasedesignPhysicaldatabasedesign.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware*4.3.4DatabasedesignLogicaldatabasedesignidentifiestheimportantobjectsthatneedtoberepresentedinthedatabaseandtherelationshipsbetweentheseobjects.

Physicaldatabasedesigndescribeshowthelogicaldesignistobephysicallyimplemented(astables)inthetargetDBMS.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware5.DBMSselection(Optional)

SelectionofanappropriateDBMStosupportthedatabasesystem.Undertakenatanytimepriortologicaldesignprovidedsufficientinformationisavailableregardingsystemrequirements.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware5.DBMSselection(Optional)

DB-Engines2015年2月數(shù)據(jù)庫排名DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.Applicationdesign

Designofuserinterfaceandapplicationprogramsthatuseandprocessthedatabase.Databaseandapplicationdesignareparallelactivities.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.Applicationdesign

Transactionisanaction,orseriesofactions,carriedoutbyasingleuserorapplicationprogramthataccessesorchangescontentofthedatabase.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.ApplicationdesignThreemaintypesoftransactions:retrievaltransactionsupdatetransactionsmixedtransactionsDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware6.ApplicationdesignGuidelinesforform/reportdesignDatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware7.Prototyping(Optional)

Buildingworkingmodelofadatabasesystem.Purposetoidentifyfeaturesofasystemthatworkwell,orareinadequate;tosuggestimprovementsorevennewfeatures;toclarifytheusers’requirements;toevaluatefeasibilityofaparticularsystemdesign.DatabaseDesign.SchoolofsoDatabaseDesign.Schoolofsoftware7.Prototyping(Optional)Requirementsprototypingdeterminestherequirementsofaproposeddatabasesyst