基于这样的三个表,即学生表 S、课程表 C 和学生选课表 SC,它们的结构 如下: S(S#,SN,SEX,AGE,DEPT
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")