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 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”)