Postgresql running total
Try this

    drop table if exists data  cascade;
    create table time_table (id int, entry_date date, hours numeric);
    insert into time_table
    values
    (1, to_date('01-01-2019', 'dd-mm-yyyy'), 1),
    (2, to_date('01-02-2019', 'dd-mm-yyyy'), 2),
    (3, to_date('01-03-2019', 'dd-mm-yyyy'), 3),
    (4, to_date('01-04-2019', 'dd-mm-yyyy'), 4),
    (5, to_date('01-05-2019', 'dd-mm-yyyy'), 5),
    (6, to_date('01-06-2019', 'dd-mm-yyyy'), 6);

    select *,
       sum(hours) over(order by entry_date asc rows between unbounded preceding 
     and current row) as running_total
     from time_table


db fiddle here: https://www.db-fiddle.com/f/ojsazNcvgfaX66CzdRDRXm/1