title: where datediff < 15 from today in query builder laravel
body: <p>I have field in my table product like this</p>
  
  <pre><code>--exp_date--
  2016-08-02
  2016-08-28
  2016-08-28
  2016-08-23
  2016-08-15
  2016-08-05
  2016-08-20
  </code></pre>
  
  <p><code>exp_date</code> already in <code>date</code> format in mysql<br>
  I want to <code>select</code> data which date remaining <code>exp_date</code> less than 15 from today</p>
  
  <p>i aleady try something like this</p>
  
  <pre><code>$dn = date('Y-m-d');          //today date
  $query = DB::table('product')-&gt;where(DB::raw('datediff(exp_date), $dn') &lt; 15)-&gt;get();
  </code></pre>
  
  <p>but i get this error <br> <code>Object of class Illuminate\Database\Query\Expression could not be converted to int</code></p>
  
  <p>how to fix it?</p>
  
  <p>ps:<br>i used laravel 4.2 and prefer it's by query builder or raw query</p>