一个是告诉了一个人头衔是啥
一个是告诉了一个人工资多少
查询的话就是将两张表连在一起就是最后的查询的总表
于是有

select t.title, avg(s.salaries)
    from titles as t join salaries as s
    where t.emp_no = s.emp_no;

又因为要各个title对应的员工薪资情况，所以要分组，以title为分组依据，将各个工资合起来
因为分组后合起来了，所以上面的用的是 avg(s.salaries)
所以，追加

select t.title, avg(s.salaries)
    from titles as t join salaries as s
    where t.emp_no = s.emp_no
    group by t.title;

因为又要按照公司平均薪资升序，于是就有

select t.title, avg(s.salaries)
    from titles as t join salaries as s
    where t.emp_no = s.emp_no
    group by t.title
    order by avg(s.salaries) asc;