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1、数据建模与分析•定义数据模型并解释其优点•理解实体-关系数据模空•数据建模的方法步骤：1.Discoverentitlesandrelationships.2.Constructanentity-relationshipcontextdiagram.3・constructakey-baseddiagram・4.Constructafullyattributedentityrelationshipdiagramanddescribedatastructuresandattributestotherepositor
2、y.5.Normalizealogicaldata•mappingdatarequirementstobusinessoperatinglocations・Datamodeling一atechniquefororganizinganddocumentingasystem'sdata・Sometimescalleddatabasemodeling・Entityrelationshipdiagram(ERD)一adatamodelutilizingseveralnotationstodepictdatainterm
3、softheentitiesandrelationshipsdescribedbythatdata.DataModelingConcepts:EntityEntity一aclassofpersons,places,objects,events,orconceptsaboutwhichweneedtocaptureandstoredata・•NamedbyasingularnounHPersons:agency,contractor,customer,department,division,employee,in
4、structor,student,supplier.HPlaces:salesregion,building,room,branchoffice,campus・QObjects:book,machine,part,product,rawmaterial,softwarelicense,softwarepackage,tool,vehiclemodel,vehicle・HEvents:application,award,cancellation,class,flight,invoice,order,registr
5、ation,renewal,requisition,reservation,sale,trip.HConcepts:account,blockoftime,bond,course,fund,qualification,stock.Entityinstance—asingleoccurreneeofanentityDataModelingConcepts:AttributesAttribute一adescriptivepropertyorcharacteristicofanentity.Synonymsinclu
6、deelement,property,andfield.•Justasaphysicalstudentcanhaveattributes,suchashaircolor,height,etc.,dataentityhasdataattributesCompoundattribute(组合属性)-anattributethatconsistsofotherattributes・SynonymsindifferentdatamodelingIanguagesarenumerous:concatenatedattri
7、bute,compositeattribute,anddatastructure・姓名包括：firstnamelastnameDataModelingConcepts:IdentificationKey一anattribute,oragroupofattributes,thatassumesauniquevalueforeachentityinstance.Itissometimescalledanidentifier.•Concatenatedkey-groupofattributesthatuniquely
8、identifiesaninstance.Synonyms:compositekey,compoundkey・（组合键）•Candidatekey一oneofanumberofkeysthatmayserveastheprimarykey.Synonym:candidateidentifier.•Primarykey一acandidatekeyusedtouniquelyidentif
