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POHow do I prevent gaps while selecting by hour in MySQL?
 

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  1. POHow do I prevent gaps while selecting by hour in MySQL?
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    <p>I have the current SQL query to select requests per hour:</p> <pre><code>SELECT ((FLOOR( unix_timestamp(request_when)/(60*60))*(60*60))*1000) as request_when, COUNT(*) as amount FROM api_requests WHERE request_when BETWEEN SUBDATE(NOW(), INTERVAL 12 HOUR) AND NOW() GROUP BY HOUR(request_when) ORDER BY id DESC; </code></pre> <p><strong>The problem</strong> is that when there are 0 rows it just doesn't return a row, which is expected based on the query. However, I would like it to return 0 (with the correct datetime/timestamp). I have played around with other queries but none of them seem to work.</p> <p>An example output of what happens now is:</p> <pre><code>1289516400000 6 1289512800000 15 1289509200000 11 1289505600000 31 1289476800000 3 </code></pre> <p>You will notice it skipped a few hours. If you don't feel like doing the math, the datetime values of those timestamps are</p> <pre><code>2010-11-11 12:00:00 3 2010-11-11 20:00:00 31 2010-11-11 21:00:00 11 2010-11-11 22:00:00 15 2010-11-11 23:00:00 7 </code></pre> <p>I would like the times without rows (hours 13-19, for example) to return "0" instead of no row. This would make my wanted output to look like this:</p> <pre><code>2010-11-11 12:00:00 3 2010-11-11 13:00:00 0 2010-11-11 14:00:00 0 2010-11-11 15:00:00 0 2010-11-11 16:00:00 0 2010-11-11 17:00:00 0 2010-11-11 18:00:00 0 2010-11-11 19:00:00 0 2010-11-11 20:00:00 31 2010-11-11 21:00:00 11 2010-11-11 22:00:00 15 2010-11-11 23:00:00 7 </code></pre> <hr> <p>I went ahead and created a "helper" or "filler" table with the hours from 00 thru 23, and I tried using a RIGHT JOIN to it, but my query returns 0 rows and doesn't work at all. This query that doesn't work looks like this:</p> <pre><code>SELECT ((FLOOR( unix_timestamp(request_when)/(60*60))*(60*60))*1000) as request_when, IFNULL(COUNT(*),0) as amount FROM api_requests RIGHT JOIN _filler ON (HOUR(api_requests.`request_when`) = _filler.`hours`) WHERE request_when BETWEEN SUBDATE(NOW(), INTERVAL 12 HOUR) AND NOW() GROUP BY HOUR(request_when) ORDER BY api_requests.id DESC; </code></pre>
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      1. POHow do I prevent gaps while selecting by hour in MySQL?
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    2. COAdded expected values and more details.
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      1. POHow do I prevent gaps while selecting by hour in MySQL?
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