SQL Running Total By Second - TimeStamp / Value - sql

Question

I'm having troubles writing a query that would aggregate my results per one second. Here I'm creating an example table and make two inserts.
create table example (
start timestamp,
stop timestamp,
qty INTEGER
);
insert into example(start, stop, qty)
values ('2019-06-11 09:59:59', '2019-06-11 10:00:04', 14);
insert into example(start, stop, qty)
values ('2019-06-11 10:00:00', '2019-06-11 10:00:03', 12);
I need a query that would return me something like this:
or
Where 1,2,3,4,5 are seconds from the first 2 inserts. 09:59:59 to 10:00:04 gives 5 seconds.
and 14, 26, 26, 26, 14 is the sum of qty for the rows with the same date.
14 + 12 = 26 and hence this number. And this addition occurs only for the seconds that occure in the same moment.
Is such a query possible?

Answer 1

In Oracle SQL, you could do something like this:
WITH test_data AS (
SELECT to_date('2019-06-11 09:59:59', 'yyyy-mm-dd hh24:mi:ss') AS start_time, to_date('2019-06-11 10:00:04', 'yyyy-mm-dd hh24:mi:ss') AS end_time, 14 AS qty FROM dual UNION ALL
SELECT to_date('2019-06-11 10:00:00', 'yyyy-mm-dd hh24:mi:ss') AS start_time, to_date('2019-06-11 10:00:03', 'yyyy-mm-dd hh24:mi:ss') AS end_time, 12 AS qty FROM dual
), seconds_between_first_last AS (
SELECT MIN(t.start_time) AS first_start_time,
MAX(t.end_time) AS last_end_time,
(MAX(t.end_time) - MIN(t.start_time)) * (24*60*60) AS seconds_elapsed /* Get the number of seconds between the first start time and the last end time */
FROM test_data t
), second_rows AS (
SELECT LEVEL AS seconds_since_start,
d.first_start_time + ((LEVEL - 1) / (24*60*60)) AS target_time
FROM seconds_between_first_last d
CONNECT BY LEVEL <= d.seconds_elapsed /* Get one row for each second in the interval */
)
SELECT r.seconds_since_start,
COALESCE(SUM(d.qty), 0) AS total_qty_in_interval
FROM second_rows r
LEFT JOIN test_data d
ON d.start_time <= r.target_time
AND d.end_time > r.target_time
GROUP BY r.seconds_since_start
ORDER BY r.seconds_since_start

Answer 2

You can get the boundaries easily enough:
with ss as (
select start as ts, qty
from t
union all
select stop, -qty
from t
)
select ts, sum(qty) as day_qty,
sum(sum(qty)) over (order by ts) as running_qty
from ss
group by ts;
This has all the timestamps when something starts or stops. It does not "fill in" values. The best way to do that depends on the database.

Answer 3

In access we have to use a workaround. See the example below.
SELECT TimeStamp, (SELECT SUM(Value) AS Total FROM Table1 WHERE Table1.TImeStamp <= T1.TimeStamp) AS Total
FROM Table1 as T1;