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