select
a.emp_no
,b.salary - a.salary growth
from
(
select
emp_no
,salary
from salaries
where from_date in (
select min(from_date)
from salaries
group by emp_no
)
) a
inner join
(
select
emp_no
,salary
from salaries
where to_date = '9999-01-01'
) b
on a.emp_no = b.emp_no
order by growth