解法1：
select s1.emp_no,(s2.salary-s1.salary) growth
from salaries s1
inner join salaries s2  
on s1.emp_no =s2.emp_no and s2.to_date='9999-01-01' 
inner join employees e 
on s1.emp_no=e.emp_no and hire_date=s1.from_date
order by growth

解法2：
select e.emp_no,a.salary-s.salary growth
from employees e 
inner join salaries s on e.emp_no =s.emp_no  and e.hire_date=s.from_date
inner join (
select emp_no,salary,to_date,lead(to_date,1,"最后一次") over(partition by emp_no order by to_date ) l 
from salaries) a 
on e.emp_no=a.emp_no
where a.to_date='9999-01-01' and l='最后一次'
order by growth