Zend framework 普通查询到Zend格式查询？

我手动构造了一个查询。。。我面临着在zend建设的斗争

e、 我在里面选择

这是我的疑问

SELECT * FROM (
  SELECT t1.eventId,t1.start_date,t1.end_date, COUNT(*) pos FROM events t1
    LEFT JOIN events t2
      ON t2.start_date = t1.start_date AND t2.eventId <= t1.eventId
  GROUP BY
    t1.eventId,t1.start_date
  ) t
WHERE
  pos <= 3;

    $query = $database->select ()
        ->from ('events AS t1', array (
        'eventId',
        'start_date',
        'end_date',
        new Zend_Db_Expr ('COUNT(*) AS pos')
    ))
        ->joinLeft ('events AS t2', 't2.start_date = t1.start_date AND t2.eventId <= t1.eventId', array ())
        ->group ('t1.eventId,t1.start_date');

    $outer_query = $database->select ()
        ->from ($query)
        ->where ('pos <= 3');