How to convert nested sql query to zend 1.12 format

Question

My Query:

select distinct ml.send_to from message_log as ml where NOT exists
(select mobile_no from user_details WHERE user_details.mobile_no = ml.send_to);

Answer 1

$select1 = $db->select()->from('user_details',array('mobile_no'))
                  ->where('user_details.mobile_no = ml.send_to');

$select2 = $db->select()->distinct()
               ->from(array('ml'=>'message_log'), array('ml.send_to')))
               ->where('NOT EXISTS ?', $select1);

This will do the trick in the easiest way.