(38)至(41)题基于“学生—选课-课程”数据库中的三个关系:
S(S#,SNAME,SEX,AGE),SC(S#,C#,GRADE),C(C#,CNAME,TEACHER)
查询选修了课程号为“C2”的学生号和姓名,若用下列SQL的SELECT语句表达时,哪一个是错误的
A.SELECT S.S#,SNAME FROM S WHERE S.S#
=(SELECT SC.S#FROM SC WHERE C#=‘C2’
B.SELECT S.S#,SNAME FROM S,SC
WHERE S.S#=SC.S# AND C#=‘C2’)
C.SELECT S.S#,SNAME FROM S,SC
WHERE S.S#=SC.S# AND C#=‘C2 ORDER BY S.S#
D.SELECT S.S#,SNAME FROM S WHERE S.S#
IN(SELECT SC.S# FORM SC WHERE C#=‘C2’)