title: Select MAX(timestamp) GROUP BY
body: <p>I have the following table:</p>
  
  <pre><code>+----+----------+---------+--------+-------+---------------------+
  | id | order_id | user_id | status | notes | timestamp           |
  +----+----------+---------+--------+-------+---------------------+
  |  3 |        1 |       0 |      0 |       | 2015-11-29 22:49:44 |
  |  4 |        1 |       0 |      2 |       | 2015-11-29 22:51:51 |
  |  5 |        2 |       0 |      0 |       | 2015-11-29 23:14:26 |
  |  6 |        3 |       0 |      0 |       | 2015-11-29 23:15:52 |
  +----+----------+---------+--------+-------+---------------------+
  </code></pre>
  
  <p>Why is the following query:</p>
  
  <pre><code>SELECT
      order_id,
      `status`,
      MAX(timestamp)
  FROM
      order_status
  GROUP BY
      order_id
  </code></pre>
  
  <p>Returning the following result?</p>
  
  <pre><code>+----------+--------+---------------------+
  | order_id | status | MAX(timestamp)      |
  +----------+--------+---------------------+
  |        1 |      0 | 2015-11-29 22:51:51 |
  |        2 |      0 | 2015-11-29 23:14:26 |
  |        3 |      0 | 2015-11-29 23:15:52 |
  +----------+--------+---------------------+
  </code></pre>
  
  <p>Shouldn't line 1 have status = 2?</p>