select
t.emp_no,
t.salary,
sum(salary)over(order by t.emp_no) running_total
from salaries t
where t.to_date='9999=-01-01'
或
select t1.emp_no, t1.salary, sum(t2.salary) as running_total
from salaries t1 
join salaries t2 
on t1.emp_no >= t2.emp_no
where t1.to_date="9999-01-01" and t2.to_date="9999-01-01"
group by 1,2