title: count in sub-query in zend framework 2
body: <p>I am new bee of Zf2, so please suggest how should I create following sql in Zend framework 2?</p>
  
  <p>Select mt1.*, 
  (select count(mt2.parent_id)
   from md_type as mt2 
   where mt2.parent_id = mt1.id)) as cnt
  from md_type as mt1</p>