假设有三个基本表：学生表S、课程表C、学生选课表SC，它们的结构如下：S（S#，SN，SEX，AGE，DEPT)C（C#，CN)SC（S#，C#，GRADE)检索选修课程“C2”的学生中成绩最高的学生的学号，正确的SELECT语句是（)。

A.SELECT SN，AGE，SEX FROM S WHERE AGE＞(SELECT AGE FROM S WHERE SN=”王华”)

B.SELECT SN，AGE，SEX FROM S WHERE SN=”王华”

C.SELECT SN，AGE，SEX FROM S WHERE AGE＞(SELECT AGE WHERE SN=”王华”)

D.SELECT SN，AGE，SEX FROM S WHERE AGE＞王华.AGE

A.SELECT SN，AGE，SEX FROM S WHERE AGE＞(SELECT AGE FROM S WHERE SN=”王华”)

B.SELECT SN，AGE，SEX FROM S WHERE SN=”王华”

C.SELECT SN，AGE，SEX FROM S WHERE AGE＞(SELECT AGE WHERE SN=”王华”)

D.SELECT SN，AGE，SEX FROM S WHERE AGE＞王华.AGE

A.SELECT S# FROM SC WHERE C#=”C2” AND GRADE＞=(SELECT GRADE FROM SC WHERE C#= “C2”)

B.SELECT S# FROM SC WHERE C#=”C2” AND GRADE IN (SELECT GRADE FROM SC WHERE C#= “C2”)

C.SELECT S# FROM SC WHERE C#=”C2” AND GRADE NOT IN (SELECT GRADE FROM SC WHERE C#= “C2”)

D.SELECT S# FROM SC WHERE C#=”C2” AND GRADE＞=ALL (SELECT GRADE FROM SC WHERE C#= “C2”)

A.SELECT S# FROM SC WHERE C#=”C2” AND GRADE＞=(SELECT GRADE FROM SC WHERE C#= “C2”)

B.SELECT S# FROM SC WHERE C#=”C2” AND GRADE IN (SELECT GRADE FROM SC WHERE C#= “C2”)

C.SELECT S# FROM SC WHERE C#=”C2” AND GRADE NOT IN (SELECT GRADE FROM SC WHERE C#= “C2”)

D.SELECT S# FROM SC WHERE C#=”C2” AND GRADE＞=ALL (SELECT GRADE FROM SC WHERE C#= “C2”)

设教学数据库中有三个基本表：

学生表S(SNO，SNAME，AGE，SEX)，其属性分别表示学号、学生姓名、年龄、性别。

课程表C(CNO，CNAME，TEACHER)，其属性分别表示课程号、课程名、上课教师名。

选修表SC(SNO，CNO，GRADE)，其属性分别表示学号、课程号、成绩。

请完成下列问题：

(1)写出查询张三同学没有选修的课程的课程号的SQL查询语句;

(2)用等价的关系代数表达式表示上述SQL查询语句。

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*

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*

FROM C

WHERE Teacher=‘LIU’))

D) SELECT Sname

FROM S WHERE Ssex=‘F’AND EXISTS(SELECT*

FROM SC

WHERE SC.Sno=S.Sno AND EXISTS

(SELECT*

FROM C

WHERE C.Cno=SC.Cno AND Teacher=‘LIU’))

A.SELECT SNAME, SAGE, SSEX FROM S WHERE SAGE ＞ (SELECT SAGE FROM S WHERE SNO = '20180601011');

B.SELECT SNAME, SAGE, SSEX FROM S WHERE SNO = '20180601011');

C.SELECT SNAME, SAGE, SSEX FROM S WHERE SAGE＞ (SELECT SAGE WHERE SNO = '20180601011');

D.SELECT SNAME, SAGE, SSEX FROM S WHERE SAGE＞'20180601011'.SAGE;