title: Column Ambiguous Error in Laravel 4
body: <p>I have a query below in Laravel 4. in lists, I did specified 'units.unit' but I got column ambiguous error. </p>
  
  <pre><code>$unit = Unit::join('bookings','bookings.unit','=','units.unit')-&gt;where('bookings.id', '=', $id)-&gt;lists('units.unit', 'units.id');
  </code></pre>
  
  <blockquote>
    <p>SQLSTATE[23000]: Integrity constraint violation: 1052 Champ: 'unit' dans field list est ambigu (SQL: select <code>unit</code>, <code>units</code>.<code>id</code> from <code>units</code> inner join <code>bookings</code> on <code>bookings</code>.<code>unit</code> = <code>units</code>.<code>unit</code> where <code>bookings</code>.<code>id</code> = 22)</p>
  </blockquote>
  
  <p>Where goes wrong?</p>