1 select t.stuid, t.stuname, t.classcode, t1.classname, t1.grade
2   from astudents t, aclass_lj t1
3  where t.classcode(+) = t1.classcode;

select t.stuid, t.stuname, t.classcode, t1.classname, t1.grade
  from astudents t, aclass_lj t1
 where t.classcode = t1.classcode(+);