数据库系统基础教程第二章答案汇编.docx
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数据库系统基础教程第二章答案汇编
Exercise2.2.1a
ForrelationAccounts,theattributesare:
acctNo,type,balance
ForrelationCustomers,theattributesare:
firstName,lastName,idNo,account
Exercise2.2.1b
ForrelationAccounts,thetuplesare:
(12345,savings,12000),
(23456,checking,1000),
(34567,savings,25)
ForrelationCustomers,thetuplesare:
(Robbie,Banks,901-222,12345),
(Lena,Hand,805-333,12345),
(Lena,Hand,805-333,23456)
Exercise2.2.1c
ForrelationAccountsandthefirsttuple,thecomponentsare:
123456→acctNo
savings→type
12000→balance
ForrelationCustomersandthefirsttuple,thecomponentsare:
Robbie→firstName
Banks→lastName
901-222→idNo
12345→account
Exercise2.2.1d
ForrelationAccounts,arelationschemais:
Accounts(acctNo,type,balance)
ForrelationCustomers,arelationschemais:
Customers(firstName,lastName,idNo,account)
Exercise2.2.1e
Anexampledatabaseschemais:
Accounts(
acctNo,
type,
balance
)
Customers(
firstName,
lastName,
idNo,
account
)
Exercise2.2.1f
Asuitabledomainforeachattribute:
acctNo→Integer
type→String
balance→Integer
firstName→String
lastName→String
idNo→String(becausethereisahyphenwecannotuseInteger)
account→Integer
Exercise2.2.1g
AnotherequivalentwaytopresenttheAccountrelation:
acctNo
balance
type
34567
25
savings
23456
1000
checking
12345
12000
savings
AnotherequivalentwaytopresenttheCustomersrelation:
idNo
firstName
lastName
account
805-333
Lena
Hand
23456
805-333
Lena
Hand
12345
901-222
Robbie
Banks
12345
Exercise2.2.2
Examplesofattributesthatarecreatedforprimarilyservingaskeysinarelation:
UniversalProductCode(UPC)usedwidelyinUnitedStatesandCanadatotrackproductsinstores.
SerialNumbersonawidevarietyofproductstoallowthemanufacturertoindividuallytrackeachproduct.
VehicleIdentificationNumbers(VIN),auniqueserialnumberusedbytheautomotiveindustrytoidentifyvehicles.
Exercise2.2.3a
Wecanorderthethreetuplesinanyof3!
=6ways.Also,thecolumnscanbeorderedinanyof3!
=6ways.Thus,thenumberofpresentationsis6*6=36.
Exercise2.2.3b
Wecanorderthethreetuplesinanyof5!
=120ways.Also,thecolumnscanbeorderedinanyof4!
=24ways.Thus,thenumberofpresentationsis120*24=2880
Exercise2.2.3c
Wecanorderthethreetuplesinanyofm!
ways.Also,thecolumnscanbeorderedinanyofn!
ways.Thus,thenumberofpresentationsisn!
m!
Exercise2.3.1a
CREATETABLEProduct(
makerCHAR(30),
modelCHAR(10)PRIMARYKEY,
typeCHAR(15)
);
Exercise2.3.1b
CREATETABLEPC(
modelCHAR(30),
speedDECIMAL(4,2),
ramINTEGER,
hdINTEGER,
priceDECIMAL(7,2)
);
Exercise2.3.1c
CREATETABLELaptop(
modelCHAR(30),
speedDECIMAL(4,2),
ramINTEGER,
hdINTEGER,
screenDECIMAL(3,1),
priceDECIMAL(7,2)
);
Exercise2.3.1d
CREATETABLEPrinter(
modelCHAR(30),
colorBOOLEAN,
typeCHAR(10),
priceDECIMAL(7,2)
);
Exercise2.3.1e
ALTERTABLEPrinterDROPcolor;
Exercise2.3.1f
ALTERTABLELaptopADDodCHAR(10)DEFAULT‘none’;
Exercise2.3.2a
CREATETABLEClasses(
classCHAR(20),
typeCHAR(5),
countryCHAR(20),
numGunsINTEGER,
boreDECIMAL(3,1),
displacementINTEGER
);
Exercise2.3.2b
CREATETABLEShips(
nameCHAR(30),
classCHAR(20),
launchedINTEGER
);
Exercise2.3.2c
CREATETABLEBattles(
nameCHAR(30),
dateDATE
);
Exercise2.3.2d
CREATETABLEOutcomes(
shipCHAR(30),
battleCHAR(30),
resultCHAR(10)
);
Exercise2.3.2e
ALTERTABLEClassesDROPbore;
Exercise2.3.2f
ALTERTABLEShipsADDyardCHAR(30);
Exercise2.4.1a
R1:
=σspeed≥3.00(PC)
R2:
=πmodel(R1)
model
1005
1006
1013
Exercise2.4.1b
R1:
=σhd≥100(Laptop)
R2:
=Product
(R1)
R3:
=πmaker(R2)
maker
E
A
B
F
G
Exercise2.4.1c
R1:
=σmaker=B(Product
PC)
R2:
=σmaker=B(Product
Laptop)
R3:
=σmaker=B(Product
Printer)
R4:
=πmodel,price(R1)
R5:
=πmodel,price(R2)
R6:
=πmodel,price(R3)
R7:
=R4
R5
R6
model
price
1004
649
1005
630
1006
1049
2007
1429
Exercise2.4.1d
R1:
=σcolor=trueANDtype=laser(Printer)
R2:
=πmodel(R1)
model
3003
3007
Exercise2.4.1e
R1:
=σtype=laptop(Product)
R2:
=σtype=PC(Product)
R3:
=πmaker(R1)
R4:
=πmaker(R2)
R5:
=R3–R4
maker
F
G
Exercise2.4.1f
R1:
=ρPC1(PC)
R2:
=ρPC2(PC)
R3:
=R1
(PC1.hd=PC2.hdANDPC1.model<>PC2.model)R2
R4:
=πhd(R3)
hd
250
80
160
Exercise2.4.1g
R1:
=ρPC1(PC)
R2:
=ρPC2(PC)
R3:
=R1
(PC1.speed=PC2.speedANDPC1.ram=PC2.ramANDPC1.modelR4:
=πPC1.model,PC2.model(R3)
PC1.model
PC2.model
1004
1012
Exercise2.4.1h
R1:
=πmodel(σspeed≥2.80(PC))
πmodel(σspeed≥2.80(Laptop))
R2:
=πmaker,model(R1
Product)
R3:
=ρR3(maker2,model2)(R2)
R4:
=R2
(maker=maker2ANDmodel<>model2)R3
R5:
=πmaker(R4)
maker
B
E
Exercise2.4.1i
R1:
=πmodel,speed(PC)
R2:
=πmodel,speed(Laptop)
R3:
=R1
R2
R4:
=ρR4(model2,speed2)(R3)
R5:
=πmodel,speed(R3
(speedR6:
=R3–R5
R7:
=πmaker(R6
Product)
maker
B
Exercise2.4.1j
R1:
=πmaker,speed(Product
PC)
R2:
=ρR2(maker2,speed2)(R1)
R3:
=ρR3(maker3,speed3)(R1)
R4:
=R1
(maker=maker2ANDspeed<>speed2)R2
R5:
=R4
(maker3=makerANDspeed3<>speed2ANDspeed3<>speed)R3
R6:
=πmaker(R5)
maker
A
D
E
Exercise2.4.1k
R1:
=πmaker,model(Product
PC)
R2:
=ρR2(maker2,model2)(R1)
R3:
=ρR3(maker3,model3)(R1)
R4:
=ρR4(maker4,model4)(R1)
R5:
=R1
(maker=maker2ANDmodel<>model2)R2
R6:
=R3
(maker3=makerANDmodel3<>model2ANDmodel3<>model)R5
R7:
=R4
(maker4=makerAND(model4=modelORmodel4=model2ORmodel4=model3))R6
R8:
=πmaker(R7)
maker
A
B
D
E
Exercise2.4.2a
Exercise2.4.2b
Exercise2.4.2c
Exercise2.4.2d
Exercise2.4.2e
Exercise2.4.2f
Exercise2.4.2g
Exercise2.4.2h
Exercise2.4.2i
Exercise2.4.2j
Exercise2.4.2k
Exercise2.4.3a
R1:
=σbore≥16(Classes)
R2:
=πclass,country(R1)
class
country
Iowa
USA
NorthCarolina
USA
Yamato
Japan
Exercise2.4.3b
R1:
=σlaunched<1921(Ships)
R2:
=πname(R1)
name
Haruna
Hiei
Kirishima
Kongo
Ramillies
Renown
Repulse
Resolution
Revenge
RoyalOak
RoyalSovereign
Tennessee
Exercise2.4.3c
R1:
=σbattle=DenmarkStraitANDresult=sunk(Outcomes)
R2:
=πship(R1)
ship
Bismarck
Hood
Exercise2.4.3d
R1:
=Classes
Ships
R2:
=σlaunched>1921ANDdisplacement>35000(R1)
R3:
=πname(R2)
name
Iowa
Missouri
Musashi
NewJersey
NorthCarolina
Washington
Wisconsin
Yamato
Exercise2.4.3e
R1:
=σbattle=Guadalcanal(Outcomes)
R2:
=Ships
(ship=name)R1
R3:
=Classes
R2
R4:
=πname,displacement,numGuns(R3)
name
displacement
numGuns
Kirishima
32000
8
Washington
37000
9
Exercise2.4.3f
R1:
=πname(Ships)
R2:
=πship(Outcomes)
R3:
=ρR3(name)(R2)
R4:
=R1
R3
name
California
Haruna
Hiei
Iowa
Kirishima
Kongo
Missouri
Musashi
NewJersey
NorthCarolina
Ramillies
Renown
Repulse
Resolution
Revenge
RoyalOak
RoyalSovereign
Tennessee
Washington
Wisconsin
Yamato
Arizona
Bismarck
DukeofYork
Fuso
Hood
KingGeorgeV
PrinceofWales
Rodney
Scharnhorst
SouthDakota
WestVirginia
Yamashiro
Exercise2.4.3g
From2.3.2,assumingthateveryclasshasoneshipnamedaftertheclass.
R1:
=πclass(Classes)
R2:
=πclass(σname<>class(Ships))
R3:
=R1–R2
class
Bismarck
Exercise2.4.3h
R1:
=πcountry(σtype=bb(Classes))
R2:
=πcountry(σtype=bc(Classes))
R3:
=R1∩R2
country
Japan
Gt.Britain
Exercise2.4.3i
R1:
=πship,result,date(Battles
(battle=name)Outcomes)
R2:
=ρR2(ship2,result2,date2)(R1)
R3:
=R1
(ship=ship2ANDresult=damagedANDdateR4:
=πship(R3)
Noresultsfromsampledata.
Exercise2.4.4a
Exercise2.4.4b
Exercise2.4.4c
Exercise2.4.4d
Exercise2.4.4e
Exercise2.4.4f
Exercise2.4.4g
Exercise2.4.4h
在调查中我们注意到大多数同学都比较注重工艺品的价格,点面氛围及服务。
关于DIY手工艺制品的消费调查Exercise2.4.4i
beadorks公司成功地创造了这样一种气氛:
商店和顾客不再是单纯的买卖关系,营业员只是起着参谋的作用,顾客成为商品或者说是作品的作参与者,营业员和顾客互相交流切磋,成为一个共同的创作体
Exercise2.4.5
据上述部分的分析可见,我校学生就达4000多人。
附近还有两所学校,和一些居民楼。
随着生活水平的逐渐提高,家长给孩子的零用钱也越来越多,人们对美的要求也越来越高,特别是大学生。
他们总希望自己的无论是衣服还是首饰都希望与众不同,能穿出自己的个性。
但在我们美丽的校园里缺少自己的个性和琳琅满目的饰品,所以我们的小饰品店存在的竞争力主要是南桥或是市区的。
这给我们小组的创业项目提供了一个很好的市场机会。
Theresultofthenaturaljoinhasonlyoneattributefromeachpairofequatedattributes.Ontheotherhand,theresultofthetheta-joinhasbothcolumnsoftheattributesandtheirvaluesareidentical.
Exercise2.4.6
大学生对手工艺制作兴趣的调研
根据调查资料分析:
大学生的消费购买能力还是有限的,为此DIY手工艺品的消费不能高,这才有广阔的市场。
Union
(2)物品的独一无二Ifweaddatupletotheargumentsoftheunionoperator,wewillgetallofthetuplesoftheoriginalresultandmaybetheaddedtuple.Iftheaddedtupleisaduplicatetuple,thenthesetbehaviorwilleliminatethattuple.Thustheunionoperatorismonotone.
(3)心态问题
价格便宜些□服务热情周到□店面装饰有个性□商品新颖多样□Intersection
Ifweaddatupletotheargumentsoftheintersectionoperator,wewillgetallofthetuplesoftheoriginalresultandmaybetheaddedtuple.Iftheaddedtupledoesnotexistintherelationthatitisaddedbutdoesexistintheotherrelation,thentheresultsetwillincludetheaddedtuple.Thustheintersectionoperatorismonotone.
图1-3大学生偏爱的手工艺品种类分布
Difference
Ifweaddatupletotheargumentsofthedifferenceoperator,wemaynotgetallofthetuplesoftheoriginalresult.SupposewehaverelationsRandSandwearecomputingR–S.SupposealsothattupletisinRbutnotinS.Theresu