title: MySQL Sum based on date range and time of day
body: <p>I have a large set of data collected every 15 minutes.  I am trying to select data between a certain time period and then within that time period divide it up by another date intervals.  And within those intervals sum over a certain time period.  </p>
  
  <p>For example, I would like to be able to select data between 01/01/2009 and 01/01/2010 and group by date ranges 01/01/2009 - 05/01/2009, 05/02/2009 - 11/01/2009, 11/02/2009 - 01/01/2010 and then within each group select the data from time 00:00:01 - 12:00:00 and 12:00:01 - 23:59:59</p>
  
  <pre><code>SELECT SUM(Data.usage)AS sum
  FROM Data.meter_id = Meter.id
  WHERE Data.start_read &gt;= '2009-01-01' 
  AND Data.end_read &lt;= '2010-01-01 23:59:59'
  </code></pre>
  
  <p>GROUP BY date range?  Not sure how to separate the data.  Thanks</p>