select sum(decode(s.grade, 1, 1)) 等级一,
       sum(decode(s.grade, 2, 1)) 等级二,
       sum(decode(s.grade, 3, 1)) 等级三,
       sum(decode(s.grade, 4, 1)) 等级四,
       sum(decode(s.grade, 5, 1)) 等级五
  from emp e, salgrade s
 where e.sal >= losal
   and e.sal <= hisal;


       等级一       等级二       等级三      等级四      等级五
---------- ---------- ---------- ---------- ----------
         3          3          2          5          1