scott案例列出工资等级人数,该怎么处理

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