Hour Wise data in mySql - mysql

Question

I have the table with following fields
Createdon(datetime)
Amount(double)
I need to find the sum of amounts for next 24 hours of the given date. If there are no results then the sum should be zero.
e.g
duration sum
0000-0001 25.43
0001-0002 36.85
0002-0003 0
.
.
.
.
0022-0023 38.56
Can you please help me creating a query to find the required solution

Answer 1

The key to your query is the ability to take any datetime value and truncate it to the nearest preceding hour. You can do that with this expression:
DATE_FORMAT(Createdon, '%Y-%m-%d %H:00')
Given, for example, 2015-04-21 14:22:05, this gives back 2015-04-21 14:00:00.
Then you use that in GROUP BY
SELECT DATE_FORMAT(Createdon, '%Y-%m-%d %H:00') Createdhour,
SUM(Amount) sum
FROM theTable
GROUP BY DATE_FORMAT(Createdon, '%Y-%m-%d %H:00')
ORDER BY DATE_FORMAT(Createdon, '%Y-%m-%d %H:00')
Finally, I think you wanted one day's worth of results. You need to add a WHERE clause to get that. The one shown here will take yesterday's results -- that is, all results from [midnight yesterday -- midnight today).
SELECT DATE_FORMAT(Createdon, '%Y-%m-%d %H:00') Createdhour,
SUM(Amount) sum
FROM theTable
WHERE CreatedOn >= DATE(NOW()) - INTERVAL 1 DAY
AND CreatedOn < DATE(NOW())
GROUP BY DATE_FORMAT(Createdon, '%Y-%m-%d %H:00')
ORDER BY DATE_FORMAT(Createdon, '%Y-%m-%d %H:00')
This is explained in greater detail at http://www.plumislandmedia.net/mysql/sql-reporting-time-intervals/
To include all hours of the day, you will need an independent source of distinct DATETIME items.
Here's a query that will do such a thing.
SELECT mintime + INTERVAL seq.seq HOUR AS CreatedHour
FROM (
SELECT DATE(NOW()) - INTERVAL 1 DAY AS mintime,
DATE(NOW()) AS maxtime
) AS minmax
JOIN seq_0_to_23 AS seq
ON seq.seq < TIMESTAMPDIFF(HOUR,mintime,maxtime)
You then need to use LEFT JOIN to pick up your data.
SELECT a.Createdhour,
SUM(Amount) sum
FROM (
SELECT mintime + INTERVAL seq.seq HOUR AS CreatedHour
FROM (
SELECT DATE(NOW()) - INTERVAL 1 DAY AS mintime,
DATE(NOW()) AS maxtime
) AS minmax
JOIN seq_0_to_23 AS seq
ON seq.seq < TIMESTAMPDIFF(HOUR,mintime,maxtime)
) a
LEFT JOIN theTable t
ON a.CreatedHour = DATE_FORMAT(t.Createdon, '%Y-%m-%d %H:00')
GROUP BY DATE_FORMAT(t.Createdon, '%Y-%m-%d %H:00')
ORDER BY DATE_FORMAT(t.Createdon, '%Y-%m-%d %H:00')
Finally, you need to somehow get that table seq_0_to_23. If you're running MariaDB, it's built in. If not...
CREATE TABLE seq_0_to_23 AS
SELECT 0 AS seq
UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3
UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6
UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12
UNION ALL SELECT 13 UNION ALL SELECT 14 UNION ALL SELECT 15
UNION ALL SELECT 16 UNION ALL SELECT 17 UNION ALL SELECT 18
UNION ALL SELECT 19 UNION ALL SELECT 20 UNION ALL SELECT 21
UNION ALL SELECT 22 UNION ALL SELECT 23
This is written up in more general form at http://www.plumislandmedia.net/mysql/filling-missing-data-sequences-cardinal-integers/