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,Teache),其中S表为学生表，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 SnameFROM S,SC,CWHERE S.Sno=SC.Sno AND SC.Cno=C.Cno AND Teacher="LIU" AND Ssex="F"
B、 SELECT SnameFROM S WHERE Ssex="F" AND Sno IN(SELECT SnoFROM SCWHERE Cno IN (SELECT Cno FROM CWHERE Teacher="LIU"))
C、 SELECT SnameFROM S WHERE Ssex="F" AND EXISTS( SELECT *FROM SCWHERE SC.Sno=S.Sno AND EXISTS(SELECT *FROM CWHERE Teacher="LIU"))
D、 SELECT SnameFROM S WHERE Ssex="F" AND EXISTS( SELECT *FROM SCWHERE SC.Sno=S.Sno AND EXISTS(SELECT *FROM CWHERE C.Cno=SC.Cno AND Teacher="LIU"))

【正确答案】 C

【答案解析】