SQL query to calculate sum of row with previous row

Question

This is my table

date     count of subscription per date
----      ----------------------------
21-03-2016      10
22-03-2016      30
23-03-2016      40 

Please need your help, I need to get the result like below table, summation second row with first row, same thing for another rows:

date     count of subscription per date
----      ----------------------------
21-03-2016      10
22-03-2016      40
23-03-2016      80 

Answer 1

Select sum(col1) over(order by date rows between unbounded preceding and current row) cnt from mytable;

Answer 2

You can do a cumulative sum using the ANSI standard analytic SUM() function:

select date, sum(numsubs) over (order by date) as cume_numsubs
from t;

Answer 3

SELECT t.date, (
    SELECT SUM(numsubs) 
    FROM mytable t2 
    WHERE t2.date <= t.date
) AS cnt
FROM mytable t