student--学生表
student_id,
student_name,
student_no
course--课程表
course_id,
course_name
sc--选课信息表
student_id,
course_id
select *
from student
where student_id not in
(select student_id
from sc
where course_id in
(select course_id from course where course_name = '1号课程'))
SELECT Sname
FROM Student
WHERE NOT EXISTS
(SELECT *
FROM SC
WHERE Student.Sno=SC.Sno AND Cno='1');