select * from Student,SC where count(*) >= 3 group by Sno

select Student.* from Student,SC where count(*) >= 3 and Student.Sno = SC.Sno group by Sno

select Student.* from Student,SC group by Sno where count(*) >= 3 and Student.Sno = SC.Sno

select * from Student where Sno in ( select Sno from SC group by Sno having count(*) >= 3)