How can i get two row from 1 in duration mysql? - mysql

Question

I have rows like:
id, start_date, end_date
0, 2000-01-01 20:00:00, 2000-01-01 21:00:00
1, 2000-01-01 23:00:00, 2000-01-02 04:00:00
And I need get reporting result like:
date | time_online
2000-01-01 | 02:00:00
2000-01-02 | 04:00:00
My solution was wrong cos i only start_date count.
SELECT DATE_FORMAT(start_date, '%Y-%m-%d') as date,
SUM(CASE WHEN EXTRACT(DAY FROM start_date) <> EXTRACT(DAY FROM end_date)
THEN
TIMESTAMPDIFF(SECOND, start_date, DATE_FORMAT(start_date + INTERVAL 1 DAY, '%Y-%m-%d'))
ELSE
TIMESTAMPDIFF(SECOND, start_date, end_date) END) time_online
FROM online
GROUP BY date
Result:
date | time_online
2000-01-01 | 02:00:00
Can someone help me?

Answer 1

What you need is a (virtual) reference table with a 24 hour timespan for each date in the online table.
You can use the table itself to do that:
SELECT
DATE(start_date) + INTERVAL 0 HOUR ref_start,
DATE(start_date) + INTERVAL 24 HOUR ref_end
FROM
online
WHERE
end_date IS NOT NULL
UNION DISTINCT
SELECT
DATE(end_date) + INTERVAL 0 HOUR ref_start,
DATE(end_date) + INTERVAL 24 HOUR ref_end
FROM
online
WHERE
end_date IS NOT NULL
The + INTERVAL 0 HOUR is not really neccesary, I added that for clarity, the same goes for the DISTINCT keyword.
If you put this in a subquery then you can get with a (kind of) self-join the records with overlaps, and the calculate the difference depending on the the values:
SELECT
DATE(r.ref_start) ref_date,
SEC_TO_TIME(SUM(TIMESTAMPDIFF(SECOND,
CASE WHEN d.start_date >= r.ref_start
THEN d.start_date
ELSE r.ref_start
END,
CASE WHEN d.end_date <= r.ref_end
THEN d.end_date
ELSE r.ref_end
END))) time_online
FROM
(
SELECT
DATE(start_date) + INTERVAL 0 HOUR ref_start,
DATE(start_date) + INTERVAL 24 HOUR ref_end
FROM
online
WHERE
end_date IS NOT NULL
UNION DISTINCT
SELECT
DATE(end_date) + INTERVAL 0 HOUR ref_start,
DATE(end_date) + INTERVAL 24 HOUR ref_end
FROM
online
WHERE
end_date IS NOT NULL
) r
JOIN
online d
ON d.end_date > r.ref_start
AND d.start_date < r.ref_end
GROUP BY ref_date