问题详情

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，错误的是()。
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# FROM SC WHERE C ＝"C2")请帮忙给出正确答案和分析，谢谢！