如何在一个pdoQuery中获取两个相关表和一个不相关的多计数？

I'm making alot of unnecessary querys into my database what causes slow time to first Byte. I'm using PHP PDO Class Wrapper Version 1.2 (Beta).

  $row = $this->baseClass->db->pdoQuery('SELECT SUM(user_have_group.user_group = 2 ) AS boosters , count(user.id ) AS created_accounts FROM `user` LEFT JOIN `user_have_group` ON user_have_group.user_id = user.id ')->result();

I manage to get counts from related tables using LEFT JOIN, but I need one more result from not related table, and I have no idea how to do it. Any advice?

I managed to make it in the following way

 $row = $this->baseClass->db->pdoQuery('SELECT a.boosters,a.created_accounts,b.happy_clients  from (SELECT SUM(user_have_group.user_group = 2 ) AS boosters , count(user.id ) AS created_accounts FROM user LEFT JOIN user_have_group ON user_have_group.user_id = user.id ) AS a,(SELECT SUM(boost_order.status="complete") AS happy_clients  FROM boost_order) AS b')->result();

Thanks chris85 for help