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1、CHAPTER7DATAMODELINGANDANALYSISChapterSevenDataModelingandAnalysisDefinesystemsmodelinganddifferentiatebetweenlogicalandphysicalsystemmodels.Definedatamodelingandexplainitsbenefits.Recognizeandunderstandthebasicconceptsandconstructsofadatamodel.Readandinterpretanentity
2、relationshipdatamodel.Explainwhendatamodelsareconstructedduringaprojectandwherethemodelsarestored.Discoverentitiesandrelationships.Constructanentity-relationshipcontextdiagram.Discoverorinventkeysforentitiesandconstructakey-baseddiagram.Constructafullyattributedentityr
3、elationshipdiagramanddescribealldatastructuresandattributestotherepositoryorencyclopedia.Normalizealogicaldatamodeltoremoveimpuritiesthatcanmakeadatabaseunstable,inflexible,andnonscalable.Describeausefultoolformappingdatarequirementstobusinessoperatinglocations.Chapter
4、MapSystemModelsAsasystemsanalystoruser,youwillconstantlydealwithunstructuredproblems.Onewaytostructuresuchproblemssitodrawmodels.Amodelisarepresentationofreality.Logicalmodelsshowwhatasystemisordoes.Theyareimplementationindependent;thatis,theydepictthesystemindependent
5、ofanytechnicalimplementation.Physicalmodelsshownotonlywhatasystemisordoes,butalsohowthesystemisphysicallyandtechnicallyimplemented.DataModelingDatamodelingisatechniquefororganizinganddocumentingasystem’sdata.Datamodelingissometimescalleddatabasemodelingbecauseadatamode
6、liseventuallyimplementedasadatabase.Itissometimescalledinformationmodeling.Theactualmodelisfrequentlycalledanentityrelationshipdiagram(ERD)becauseitdepictsdataintermsoftheentitiesandrelationshipsdescribedbythedata.SampleEntityRelationshipDiagram(ERD)Persons:agency,cont
7、ractor,customer,department,division,employee,instructor,student,supplier.Places:salesregion,building,room,branchoffice,campus.Objects:book,machine,part,product,rawmaterial,softwarelicense,softwarepackage,tool,vehiclemodel,vehicle.Events:application,award,cancellation,c
8、lass,flight,invoice,order,registration,renewal,requisition,reservation,sale,trip.Concepts:account,blockoftime,bond,co
