SQL21.查找所有员工自入职以来的薪水涨幅情况

查找所有员工自入职以来的薪水涨幅情况，给出员工编号emp_no以及其对应的薪水涨幅growth，并按照growth进行升序（注:可能有employees表和salaries表里存在记录的员工，有对应的员工编号和涨薪记录，但是已经离职了，离职的员工salaries表的最新的to_date!='9999-01-01'，这样的数据不显示在查找结果里面）

用相关子查询，可以不用连接？

select emp_no,(
    (select salary from salaries where emp_no = s.emp_no order by from_date desc limit 1) 
   -(select salary from salaries where emp_no = s.emp_no order by from_date  limit 1)
)as growth
from salaries s
group by emp_no
having max(to_date) = '9999-01-01'
order by growth;