MYSQL将日期间隔分组过去10分钟

Question

I have a database with messages and a timestamp field. I want to select the count for each minute of the past 10 minutes. This is my current query:

SELECT date_format(timestamp, '%H:%i:%s'), COUNT(*) as count
FROM test
WHERE timestamp BETWEEN DATE_SUB(NOW(), INTERVAL 10 MINUTE) AND NOW() 
GROUP by
    DATE_FORMAT(timestamp, '%i')
    ORDER BY timestamp ASC

This is almost working as I want it to, showing me the count for the past 10 minutes.

However, since I'm grouping by the timestamp, for each minute except the very last, I'm getting the count from the first database entry for each minute, making my first and last result much less than the other ones.

Like in this image :

timestamp count
11:25:35 6
11:26:03 11
11:27:05 11
11:28:01 12
11:29:03 12
11:30:05 10
11:31:01 12
11:32:03 12
11:33:05 11
11:34:01 12
11:35:03 5

What I am looking for is a way to Group by minutes using something like NOW() instead of my timestamp, like this example.

timestamp count
11:25:35 11
11:26:35 12
11:27:35 11
11:28:35 11
11:29:35 11
11:30:35 11
11:31:35 11
11:32:35 11
11:33:35 11
11:34:35 11

Thank you in advance!

Answer 1

The problem is the WHERE clause. You need to remove the excess seconds before doing the aggregation.

One method is to convert to seconds, divide by 60, truncate the number, and multiply by 60. The following converts the value back to a date/time value, so an index on that column will be used:

SELECT date_format(timestamp, '%H:%i:%s'), COUNT(*) as count
FROM test
WHERE timestamp >= from_unixtime(floor(unix_timestamp(now()) / 60) * 60) - interval 10 minute AND
      timestamp < from_unixtime(floor(unix_timestamp(now()) / 60) * 60)
GROUP BY DATE_FORMAT(timestamp, '%i')
ORDER BY timestamp ASC