title: Concat String to a number returns zero
body: <p>I'm having a table whith 'id' as pk of type int.
  When I'm doing the folowing mysql query in php activerecord</p>
  
  <p><code>Location_cat::find_by_sql("select concat('#',id) as 'id', text FROM location_cat");</code></p>
  
  <p>it returns 'id' as 0, instead of '#142'for example.</p>
  
  <p>Does anyone knows this behavior?</p>