title: FROM_UNIXTIME() not working mysql
body: <p>I have a table alert_log has column name date_dt (type varchar 50) which stores unix timestamp data 
  example data : 1518783503000</p>
  
  <pre><code>select FROM_UNIXTIME(date_dt) AS 'date_formatted' from alert_log 
  </code></pre>
  
  <p>it always returns null.please help i would like to convert the example unix data as Fri Feb 16 2018 </p>