title: doctrine query builder select from table which is not entity table
body: <p>I am struggling to find a way to use query builder to select data from a table which is not a table of some entity. method ->from() takes only class name (entity name) as a parameter. 
  something like:</p>
  
  <pre><code>$qb-&gt;select('t.id')
     -&gt;from('table_not_entity_name')
     -&gt;andWhere('t.isActive = :isActive')
     -&gt;setParameter('isActive', 1);
  </code></pre>
  
  <p>I also need to join a table of entity to an another table.</p>
  
  <pre><code>$qb-&gt;select('category.id')
      -&gt;join("t.table_name", 'category')
      -&gt;distinct();
  </code></pre>
  
  <p>Is there a way? </p>