title: How do I generate a series of hourly averages in MySQL?
body: <p>I've got data in ten minutes intervals in my table:</p>
  
  <pre><code>2009-01-26 00:00:00      12
  2009-01-26 00:10:00      1.1
  2009-01-26 00:20:00      11
  2009-01-26 00:30:00      0
  2009-01-26 00:40:00      5
  2009-01-26 00:50:00      3.4
  2009-01-26 01:00:00      7
  2009-01-26 01:10:00      7
  2009-01-26 01:20:00      7.2
  2009-01-26 01:30:00      3
  2009-01-26 01:40:00      25
  2009-01-26 01:50:00      4
  2009-01-26 02:00:00      3
  2009-01-26 02:10:00      4
  etc.
  </code></pre>
  
  <p>Is it possible to formulate a single SQL-query for MySQL which will return a series of averages over each hour?</p>
  
  <p>In this case it should return:</p>
  
  <pre><code>5.42
  8.87
  etc.
  </code></pre>