经典的部门，员工表，我要分组查询各部门的平均工资

，，，，这个，，，，算了，给别人回答吧，

select max(b) from (select avg(sal) as b, deptno from emp group by deptno)

select * from (select avg(sal) as b, deptno,row_number() over(order by avg(sal)desc) n from emp group by deptno) where n=1

select avg（e.sal）sal_avg，d.dept_name
from emp e，dept d where d.dept_id=e.dept_id
group by d.dept_name