title: mysql "between date" query works in phpmyadmin but returns nothing with PDO
body: <p>When i try to run this with php/pdo the result is empty, but when i replace the variables and echo the query and copy paste to phpmyadmin it works as it should. </p>
  
  <p>I guess that it have something to do with the BETWEEN part in the query, it works if I remove it. </p>
  
  <p>php code:</p>
  
  <pre><code>$sql = 'SELECT * from `activity` 
  WHERE `activity`.`employee_id` = :id 
  AND `activity_endtime` BETWEEN :start 
  AND :end 
  ORDER BY :order LIMIT 0 ,:limit';
  
  $date_end = date('Y-m-d',time());
  $date_start = date('Y-m-01',strtotime($date_end));
  $values = array(
  ':id' =&gt; $_SESSION['user_id'], 
  ':start' =&gt; '"'.$date_start.'"', 
  ':end' =&gt; '"'.$date_end.'"',
  ':order' =&gt; 'activity_id', 
  ':limit' =&gt; '10');
  $q-&gt;execute($values);
  
  while($r = $q-&gt;fetch(PDO::FETCH_ASSOC)){
   //does not get here after adding the between part
  }
  </code></pre>
  
  <p>The query that i get from replacing the parameters and echoing:</p>
  
  <pre><code>SELECT * from `activity` 
  WHERE `activity`.`employee_id` = 7 
  AND `activity_endtime` BETWEEN "2014-08-01" 
  AND "2014-08-18" 
  ORDER BY activity_id LIMIT 0 ,10
  </code></pre>