分为两张表
一张入职薪资表
一张现在薪资表
再将两者内连接【inner join】起来，组成一张新表

select p.emp_no,q.salary-p.salary as growth
from
(select a.emp_no,a.salary
from salaries a 
inner join employees b on a.emp_no = b.emp_no
where a.from_date = b.hire_date)  p  --入职表
inner join 
(select a.emp_no,a.salary
from salaries a
where a.to_date = '9999-01-01')  q  --现在表
on p.emp_no = q.emp_no
order by growth asc;