title: Results of count(drives) per month in time-window not correct
body: <p>Hello I have the following query to get the drives that happened per month in a time window of 12 months back. However the results are not correct for example in my test database there are only 3 drives that took place in February but in my result set it shows 9 drives.</p>
  
  <pre><code>SELECT mlist.m, count(data.month) as drvs
                       FROM users, (
                             SELECT 'Jan' AS m
                             UNION SELECT 'Feb' AS m
                             UNION SELECT 'Mar' AS m
                             UNION SELECT 'Apr' AS m
                             UNION SELECT 'May' AS m
                             UNION SELECT 'Jun' AS m
                             UNION SELECT 'Jul' AS m
                             UNION SELECT 'Aug' AS m
                             UNION SELECT 'Sep' AS m
                             UNION SELECT 'Oct' AS m
                             UNION SELECT 'Nov' AS m
                             UNION SELECT 'Dec' AS m
                            ) AS mlist LEFT JOIN (SELECT DATE_FORMAT(drives.timestamp, '%b') AS month,
                                   drives.timestamp,
                                   CONCAT(drivers.name, ' ', drivers.surname) as driver,
                                   drivers.id as driver_id
                                   FROM drives, drivers WHERE drives.user = '146'
                                   AND drives.timestamp &gt; DATE_SUB(now(), INTERVAL 12 MONTH)) data
                  ON mlist.m = data.month GROUP BY mlist.m
  </code></pre>
  
  <p>results:</p>
  
  <p>"Apr","3"
  "Aug","3"
  "Dec","6"
  "Feb","9"
  "Jan","3"
  "Jul","3"
  "Jun","3"
  "Mar","3"
  "May","3"
  "Nov","3"
  "Oct","6"
  "Sep","3"</p>