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1、一、教务管理数据库的三个基本表S(SNO,SNAME,SEX,AGE,SDEPT)SC(SNO,CNO,GRADE)C(CNO,CNAME,CPNO,CCREDIT)试用SQL查询语句表达下列操作：（1）统计有学生选修的课程门数。（2）求选修4号课程的学生的平均年龄。（3）检索姓名以WANG打头的所有学生的姓名和年龄。（4）在SC中检索成绩为空值的学生学号和课程号。（5）求年龄大于女同学平均年龄的男学生姓名和年龄。解：（1）SELECTCOUNT(DISTINCTCNO)FROMSC;（2）SELECTAVG(A
2、GE)FROMS,SCWHERES.SNO=SC.SNOANDCNO=’4’（3）SELECTSNAME,AGEFROMSWHERESNAMELIKE‘WANG%’（4）SELECTSNO,CNOFROMSCWHEREGRADEISNULL;（5）SELECTSNAME,AGEFROMStheprovisionsofelectricpowerconstructionengineeringqualitysupervisionandquality...2.4.1.1theunitworksacceptancerate
3、of100%,thequalityevaluationofatotalscoreof95orabove;2.4.1.2regulatedWeldingNDTinspection100%,regulatedweldingapassingrateof>99%,andweldbeadappearance;2.4.1.3boilerhydraulicWHERESEX=’M’ANDAGE>(SELECTAVG(AGE)FROMSWHERESEX=’F’);试用SQL更新语句表达如下更新操作：（1）往基本表S中插入一个学生元
4、组(‘200912143’，‘张晶’，21)。（2）在基本表SC中删除尚无成绩的选课元组。（3）把张成民同学在SC中的选课记录全部删去。（4）把选修高等数学课程中不及格的成绩全部改为空值。（5）把低于总平均成绩的女同学成绩提高5%。解：（1）INSERTINTOS(SNO,SNAME,AGE)VALUES(‘200912143’,’张晶’,21);（2）DELETEFROMSCWHEREGRADEISNULL;（3）DELETEFROMSCWHERESNOIN(SELECTSNOFROMSWHERESNAME=’
5、张成民’)（4）UPDATESCSETGRADE=NULLWHEREGRADE<60ANDCNOIN(SELECTCNOFROMCWHERECNAME=’高等数学’);（5）UPDATESCtheprovisionsofelectricpowerconstructionengineeringqualitysupervisionandquality...2.4.1.1theunitworksacceptancerateof100%,thequalityevaluationofatotalscoreof95orabo
6、ve;2.4.1.2regulatedWeldingNDTinspection100%,regulatedweldingapassingrateof>99%,andweldbeadappearance;2.4.1.3boilerhydraulicSETGRADE=GRADE*1.05WHERESNOIN(SELECTSNOFROMSWHERESEX=’F’)ANDGRADE<(SELECTAVG(GRADE)FROMSC);二、假设某“仓库管理”关系模型有下列五个关系模式：零件PART(PNO,PNAME,COL
7、OR,WEIGHT)项目PROJECT(JNO,JNAME,JDATE)供应商SUPPLIER(SNO,SNAME,SADDR)供应P_P(JNO,PNO,TOTAL)采购P_S(PNO,SNO,QUANTITY)试用SQL语句定义上述五个基本表，并说明主键和外键。解：CREATETABLEPART(PNOCHAR(6),PNAMECHAR(10)NOTNULL,COLORCHAR(6),WEIGHTFLOAT(6),PRIMARYKEY(PNO));CREATETABLEPROJECT(JNOCHAR(6),J
8、NAMECHAR(12)NOTNULL,DATEDATE,theprovisionsofelectricpowerconstructionengineeringqualitysupervisionandquality...2.4.1.1theunitworksacceptancerateof100%,thequalityevaluationofatotalscoreof9
