use student_class
select student.*
from student,sc
where student.sclass=sc.sclass and student.sno=sc.sno
and sc.sclass='1'and  cno='2' and grade <=all
(
 select grade 
from sc ,student
where cno='2'and
student.sclass=sc.sclass and student.sno=sc.sno
and sc.sclass='1'
)