title: MySQL order by multiple case statements
body: <p>I have a situation where I need to sort my records by their "status" which is made up of a combination of fields. Here is an example how it should return the results sorted by status in ascending order:</p>
  
  <pre><code>        |     Sent      Received         Approved
  --------------------------------------------------
  record1 |     null        null             null
  record2 |  2012-01-01     null             null
  record3 |  2012-01-01   2012-01-01         null
  record4 |  2012-01-01   2012-01-01      2012-01-01
  </code></pre>
  
  <p>How would I create a MySQL query that would order these records by their overall "status"?</p>