title: Query to return all the days of a month
body: <p>This problem is related to this, which has no solution in sight: <a href="https://stackoverflow.com/questions/15548703/report-schedule/15554016?noredirect=1#comment22044254_15554016">here</a></p>
  <p>I have a table that shows me all sessions of an area.</p>
  <p>This session has a start date.</p>
  <p>I need to get all the days of month of the start date of the session by specific area (in this case)</p>
  <p>I have this query:</p>
  <pre><code>SELECT idArea, idSession, startDate FROM SessionsPerArea WHERE idArea = 1
  
  idArea | idSession |  startDate  |
     1   |    1      |  01-01-2013 |
     1   |    2      |  04-01-2013 |
     1   |    3      |  07-02-2013 |
  </code></pre>
  <p>And i want something like this:</p>
  <pre><code>    date     |  Session    |
  01-01-2013   |    1        |
  02-01-2013   |    NULL     |
  03-01-2013   |    NULL     |
  04-01-2013   |    1        |
  ........     |             |
  29-01-2013   |   NULL      |
  30-01-2013   |   NULL      |
  </code></pre>
  <p>In this case, the table returns me all the days of January.</p>
  <p>The second column is the number of sessions that occur on that day, because there may be several sessions on the same day.</p>
  <p>Anyone can help me?</p>