【单选题】对于教学数据库的三个基本表:S(Sno,Sname,Ssex),SC(Sno,Cno,Grade),C(Cno,Cname, Teacher),其中S为学生表,SC为学生选课表,C为课程表,则对于语句:检索至少选修LIU老师所授课课程中一门课程的女生姓名,SQL语句错误的是______。
A.
SELECT Sname FROM S,SC,C WHERE S.Sno=SC.Sno AND SC.Cno=C.Cno AND Teacher=‘LIU’AND Ssex=‘F’
B.
SELECT Sname FROM S WHERE Ssex=‘F’AND Sno IN (SELECT Sno FROM SC WHERE Cno IN(SELECT Cno FROM C WHERE Teacher=‘LIU’))
C.
SELECT Sname FROM S WHERE Ssex=‘F’AND EXISTS (SELECT* FROM SC WHERE SC.Sno=S.Sno AND EXISTS (SELECT*
D.
SELECT Sname FROM S WHERE Ssex=‘F’AND EXISTS(SELECT* FROM SC WHERE SC.Sno=S.Sno AND EXISTS (SELECT*
【单选题】在本实验整流、滤波电路中如果在变压器付方输出电压U2=12V时,用万用表直流档测量的U0值为5.4V,可能出了什么故障?
【单选题】在本实验整流、滤波电路中,如果变压器付方输出电压U2=12V时,用万用表直流档测量滤波后负载的电压U0值为10.8V,可能出了什么故障?
【多选题】从student(sno,sname...)表和sc(sno,cno...)表,查询选修001号课程的学生姓名,下列语句表达正确的是( )。
A.
select sname from student,sc where student.sno=sc.sno and cno='001'
B.
select sname from student where sno = (select sno from sc where cno='001')
C.
select sname from student where sno in (select sno from sc where cno='001')
D.
select sname from student where exists (select * from student where cno='001' )
【单选题】设有关系S(SNO,SNAME,SEX),C(CNO,CNAME),SC(SNO,CNO,GRADE)。其中SNO为学生号,SNAME为学生姓名,SEX为性别,CNO为课程号,CNAME为课程名。要查询选修“计算机”课的全体女学生姓名的SQL语句是SELECTSNAMEFROMS,C,SC WHERE子句。这里WHERE子句的内容是
A.
S.SNO=SC.SNO andSEX='女'andCNAME='计算机'
B.
S.SNO=SC.SNO andC.CNO=SC.CNO andCNAME='计算机'
D.
S.SNO=SC.SNO andC.CNO=SC.CNO andSEX='女'andCNAME='计算机'
【简答题】对于教学数据库的三个基本表:S(Sno,Sname,S),SC(Sno,Cno,Grade),C(Cno,Cname, Teacher),其中S为学生表,SC为学生选课表,C为课程表,则对于语句:检索至少选修LIU老师所授课课程中一门课程的女生姓名,SQL语句错误的是______。 A) SELECT Sname FROM S,SC,C WHERE S.Sno=SC.Sno AND SC.C...