title: doctrine2 dql, use setParameter with % wildcard when doing a like comparison
body: <p>I want to use the parameter place holder - e.g. ?1 - with the % wild cards. that is, something like: "u.name LIKE %?1%" (though this throws an error). The docs have the following two examples:
  1.</p>
  
  <pre><code>// Example - $qb-&gt;expr()-&gt;like('u.firstname', $qb-&gt;expr()-&gt;literal('Gui%'))
  public function like($x, $y); // Returns Expr\Comparison instance
  </code></pre>
  
  <p>I do not like this as there is no protection against code injection.</p>
  
  <p>2.</p>
  
  <pre><code>// $qb instanceof QueryBuilder
  
  // example8: QueryBuilder port of: "SELECT u FROM User u WHERE u.id = ?1 OR u.nickname LIKE ?2 ORDER BY u.surname DESC" using QueryBuilder helper methods
  $qb-&gt;select(array('u')) // string 'u' is converted to array internally
     -&gt;from('User', 'u')
     -&gt;where($qb-&gt;expr()-&gt;orx(
         $qb-&gt;expr()-&gt;eq('u.id', '?1'),
         $qb-&gt;expr()-&gt;like('u.nickname', '?2')
     ))
     -&gt;orderBy('u.surname', 'ASC'));
  </code></pre>
  
  <p>I do not like this because I need to search for terms within the object's properties - that is, I need the wild cards on either side.</p>