title: Left Outer Join doesn't return all rows from my left table?
body: <p>I am trying to get the number of page opens on a per day basis using the following query.</p>
  <pre><code>SELECT day.days, COUNT(*) as opens 
  FROM day 
  LEFT OUTER JOIN tracking ON day.days = DAY(FROM_UNIXTIME(open_date)) 
  WHERE tracking.open_id = 10 
  GROUP BY day.days
  </code></pre>
  <p>The output I get it is this:</p>
  <pre><code>days opens
  1   9
  9   2
  </code></pre>
  <p>The thing is, in my day table, I have a single column that contains the number 1 to 30 to represent the days in a month. I did a left outer join and I am expecting to have all days show on the days column!</p>
  <p>But my query is doing that, why might that be?</p>