title: "Every derived table must have its own alias" Mysql Error
body: <p>Whats wrong with my query:</p>
  
  <pre><code>SELECT minDate, deviceType, COUNT(*)
  FROM (SELECT visitorId, deviceType, 
                 MIN(sessionDate) as minDate
        FROM sessions
        GROUP BY visitorId)
  WHERE minDate &gt; DATE_SUB(NOW(), INTERVAL 14 DAY)
  GROUP BY minDate, deviceId
  </code></pre>
  
  <p>I've got this message: </p>
  
  <blockquote>
    <p>Query Error: Error: ER_DERIVED_MUST_HAVE_ALIAS: Every derived table must have its own alias</p>
  </blockquote>