Como imprimir a consulta sql exata no framework zend?

Objetos selecionados possuem um método __toString() no Zend Framework.

Do manual do Zend Framework:

$select = $db->select()
             ->from('products');

$sql = $select->__toString();
echo "$sql\n";

// The output is the string:
//   SELECT * FROM "products"

Uma solução alternativa seria usar o Zend_Db_Profiler.i.e.

$db->getProfiler()->setEnabled(true);

// your code
$this->update($up_value,'customer_id ='.$userid.' and address_id <> '.$data['address_Id']); 

Zend_Debug::dump($db->getProfiler()->getLastQueryProfile()->getQuery());
Zend_Debug::dump($db->getProfiler()->getLastQueryProfile()->getQueryParams());
$db->getProfiler()->setEnabled(false);

http://framework.zend.com/manual/en/zend .db.select.html