从ER到LogicalSchema兼谈SchemaIntegration

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1、從ER到LogicalSchema──兼談SchemaIntegration國立中央大學資訊管理系范錚強20071中央大學。范錚強準備LogicalSchema資料模型和流程模型的整合充實、調整資料模型設計關連式資料庫LogicalSchema2中央大學。范錚強資料模型和流程模型的整合修訂模式修改DFD中的datastore，消除所有「迷糊帳」所有datastore相對到相關的實體或關係建立資料典DD:DataDictionary平衡Balancing原則EverydataflowanddatastoremustbedefinedintheDD,ViceVersaEve

2、rydatastoremustcorrespondtoanentityorrelationshiptypeObjectnamesintheDD,ERDandDFDmustmatchDDentriesmustapplytoboththeDFDandERDmodel3中央大學。范錚強充實、調整資料模型AttributingandRefiningAttributingallentityandrelationshiptypesEachattributeshouldassociatewiththecorrespondingentityorrelationshiptypeTheval

3、ueoftheattributeshouldsolelydepends(fullyfunctionallydependent,FDD)ontheassociatedelementintheentityorrelationshiptypeIdentifyanidentifyingattributesforeachentitytypeandandanycompoundentitytypeIftherearemanycandidates,pickonethatisthemostappropriate.4中央大學。范錚強充實、調整資料模型(2)Eliminateallmulti-

4、valuedattributeswithappropriaterelationshipsAttributethenewE/RtypesCompanyNameCompanyNamemn5中央大學。范錚強資料模型、邏輯資料庫設計、實體資料庫設計ProcessE-Rdatamodel-->Logicaldatabasedesign-->physicaldatabasedesignANSISPARCthreetierDBarchitectureEnterpriseviewsUserviewsPhysicalviewsPhysicalEnterpriseuser6中央大學。范錚強設

5、計關連式資料庫LogicalSchemaForeachentitytype:EachEntitytypebecomesaTableEveryattributebecomesacolumnTheidentifyingattributefortheentitytypebecomesthekeyfortheTableForeachm-nrelationshiptypeEachm-nrelationshiptypebecomesaTableEveryattributebecomesacolumnTheidentifyingattributeoftheassociatedentit

6、ytypesbecomesthecompoundkeys7中央大學。范錚強關連式資料庫LogicalSchema(2)Foreach1-nrelationshiptypeSameasm-nrelationshipOnlythen-sideidentifierbecomesthekey,the1-sideidentifierbecomesanon-key(foreignkey)columnForeach1-1relationshiptypeSameas1-nrelationshipPicktheidentifierfromthemostappropriateassociat

7、edentitytypeasthekey,theotheraforeignkey8中央大學。范錚強關連式資料庫LogicalSchema(3)ForeachcompoundentitytypeForthecompoundentitytypesthatdonothaveitsownidentifier,sameasrelationshipOtherwise,usetheidentifierasthekey,andtaketheidentifyingattributeoftheassociatedentitytypesasnon-