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1、WORD文档可编辑Exercise2.2.1aForrelationAccounts,theattributesare:acctNo,type,balanceForrelationCustomers,theattributesare:firstName,lastName,idNo,accountExercise2.2.1bForrelationAccounts,thetuplesare:(12345,savings,12000),(23456,checking,1000),(34567,savings,25)F
2、orrelationCustomers,thetuplesare:(Robbie,Banks,901-222,12345),(Lena,Hand,805-333,12345),(Lena,Hand,805-333,23456)Exercise2.2.1cForrelationAccountsandthefirsttuple,thecomponentsare:123456àacctNosavingsàtype12000àbalanceForrelationCustomersandthefirsttuple,the
3、componentsare:RobbieàfirstNameBanksàlastName901-222àidNo12345àaccountExercise2.2.1dForrelationAccounts,arelationschemais:Accounts(acctNo,type,balance)ForrelationCustomers,arelationschemais:Customers(firstName,lastName,idNo,account)Exercise2.2.1eAnexampledata
4、baseschemais:Accounts(acctNo,type,balance)Customers(firstName,lastName,idNo,account)Exercise2.2.1fAsuitabledomainforeachattribute:acctNoàIntegertypeàStringbalanceàIntegerfirstNameàStringlastNameàString技术资料专业分享WORD文档可编辑idNoàString(becausethereisahyphenwecanno
5、tuseInteger)accountàIntegerExercise2.2.1gAnotherequivalentwaytopresenttheAccountrelation:acctNobalancetype3456725savings234561000checking1234512000savingsAnotherequivalentwaytopresenttheCustomersrelation:idNofirstNamelastNameaccount805-333LenaHand23456805-33
6、3LenaHand12345901-222RobbieBanks12345Exercise2.2.2Examplesofattributesthatarecreatedforprimarilyservingaskeysinarelation:UniversalProductCode(UPC)usedwidelyinUnitedStatesandCanadatotrackproductsinstores.SerialNumbersonawidevarietyofproductstoallowthemanufact
7、urertoindividuallytrackeachproduct.VehicleIdentificationNumbers(VIN),auniqueserialnumberusedbytheautomotiveindustrytoidentifyvehicles.Exercise2.2.3aWecanorderthethreetuplesinanyof3!=6ways.Also,thecolumnscanbeorderedinanyof3!=6ways.Thus,thenumberofpresentatio
8、nsis6*6=36.Exercise2.2.3bWecanorderthethreetuplesinanyof5!=120ways.Also,thecolumnscanbeorderedinanyof4!=24ways.Thus,thenumberofpresentationsis120*24=2880Exercise2.2.3cWecanorderthethreetuplesina
