基于这样的3个表,即学生表S、课程表C和学生选课表SC,它们的关系模式如下: S(S#,SN,SEX,AGE,DEPT)(学号,姓名,性别,年龄,系别) C(C#,CN)(课程号,课程名称) SC(S#,C#,GRADE)(学号,课程号,成绩) 检索选修课程“C2”的学生中成绩最低的学生的学号。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 GORM SC WHERE C#='C2')
D.SELECT S# FROM SC WHERE C#='C2' AND GRADE<=ALL(SELECT GRADE FROM SC WHERE C#='C2')