菜鸟问题

Question

select department_id ,salary from hr.employees 
join (select department_id ,max(salary) salary from hr.employees group by department_id) t
on ( hr.employees.department_id = t.department_id and hr.employees.salary = t.salary );为什么会提示 ：ora-00918 未明确定义列  
呵呵，我感觉应该没错啊，自学中……请给予支持！谢谢

Answer 1

select t.department_id ,t.salary from hr.employees 
join (select department_id ,max(salary) salary from hr.employees group by department_id) t 
on ( hr.employees.department_id = t.department_id and hr.employees.salary = t.salary );