统计出当前各个title类型对应的员工当前薪水对应的平均工资
统计出当前各个title类型对应的员工当前薪水对应的平均工资
https://www.nowcoder.com/practice/c8652e9e5a354b879e2a244200f1eaae
select distinct title, avg(salary) over(partition by title) avg_salary from titles left join salaries using(emp_no) order by avg_salary
select 需要去重,否则会重复输出