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Chapter8NormalizationTransparencies1?PearsonEducationLimited,2004Chapter8-ObjectivesHowtablesthatcontainredundantdatacansufferfromupdateanomalies,whichcanintroduceinconsistenciesintoadatabase.Therulesassociatedwiththemostcommonlyusednormalforms,namelyfirst(1NF),second(2NF),andthird(3NF).Theidentificationofvarioustypesofupdateanomaliessuchasinsertion,deletion,andmodificationanomalies.2?PearsonEducationLimited,2004Chapter8-ObjectivesHowtablesthatbreaktherulesof1NF,2NF,and3NFarelikelytocontainredundantdataandsufferfromupdateanomalies.Howtorestructuretablesthatbreaktherulesof1NF,2NF,and3NF.3?PearsonEducationLimited,2004NormalizationAtechniqueforproducingasetoftableswithdesirablepropertiesthatsupporttherequirementsofauserorcompany.4?PearsonEducationLimited,2004DataredundancyandupdateanomaliesMajoraimofrelationaldatabasedesignistogroupcolumnsintotablestominimizedataredundancyandreducefilestoragespacerequiredbybasetables.ProblemsassociatedwithdataredundancyareillustratedbycomparingtheStaffandBranchtableswiththeStaffBranchtable.5?PearsonEducationLimited,2004Dataredundancyandupdateanomalies6?PearsonEducationLimited,2004Dataredundancyandupdateanomalies7?PearsonEducationLimited,2004DataredundancyandupdateanomaliesStaffBranchtablehasredundantdata;thedetailsofabrancharerepeatedforeverymemberofstaff.Incontrast,thebranchinformationappearsonlyonceforeachbranchintheBranchtableandonlythebranchnumber(branchNo)isrepeatedintheStafftable,torepresentwhereeachmemberofstaffislocated.8?PearsonEducationLimited,2004DataredundancyandupdateanomaliesTablesthatcontainredundantinformationmaypotentiallysufferfromupdateanomalies.Typesofupdateanomaliesincludeinsertiondeletionmodification9?PearsonEducationLimited,2004Firstnormalform(1NF)Only1NFiscriticalincreatingappropriatetablesforrelationaldatabases.Allsubsequentnormalformsareoptional.Atableinwhichtheintersectionofeverycolumnandrecordcontainsonlyonevalue.10?PearsonEducationLimited,2004Branchtableisnotin1NF11?PearsonEducationLimited,2004ConvertingBranchtableto1NF12?PearsonEducationLimited,2004Secondnormalform(2NF)2NFonlyappliestotableswithcompositeprimarykeys.Atablethatisin1NFandinwhichthevaluesofeachnon-primary-keycolumncanbeworkedoutfromthevaluesinallthecolumnsthatmakeuptheprimarykey.13?PearsonEducationLimited,2004TempStaffAllocationtableisnotin2NF14?PearsonEducationLimited,2004FunctionaldependencyTheparticularrelationshipsthatweshowbetweenthecolumnsofatablearemoreformallyreferredtoasfunctionaldependencies.Functionaldependencydescribestherelationshipbetweencolumnsinatable.15?PearsonEducationLimited,2004FunctionaldependencyForexample,consideratablewithcolumnsAandB,whereBisfunctionallydependentonA(denotedA

B).IfweknowthevalueofA,wefindonlyonevalueofBinalltherecordsthathasthisvalueofA,atanymomentintime.16?PearsonEducationLimited,2004Secondnormalform(2NF)Formaldefinitionof2NFisatablethatisin1NFandeverynon-primary-keycolumnisfullyfunctionaldependentontheprimarykey.FullfunctionaldependencyindicatesthatifAandBarecolumnsofatable,BisfullydependentonAifBisfunctionallydependentonAbutnotonanypropersubsetofA.17?PearsonEducationLimited,2004ConvertingTempStaffAllocation

tableto2NF18?PearsonEducationLimited,2004Thirdnormalform(3NF)Atablethatisin1NFand2NFandinwhichallnon-primary-keycolumncanbeworkedoutfromonlytheprimarykeycolumn(s)andnoothercolumns.19?PearsonEducationLimited,2004StaffBranchtableisnotin3NF20?PearsonEducationLimited,2004Thirdnormalform(3NF)Theformaldefinitionof3NFisatablethatisin1NFand2NFandinwhichnonon-primary-keycolumnistransitivelydependentontheprimarykey.21?PearsonEducationLimited,2004Thirdnormalform(3NF)Forexample,consideratablewithA,B,andC.IfBisfunctionaldependentonA(A

B)andCisfunctionaldependentonB(B

C),thenCistransitivelydependentonAviaB(providedthatA

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