MYSQL-在Zend中使用相關的子查詢Db

Question

我想在zend_db_select（ZF 1.12）中使用相關子查詢構建一個可用的MySql查詢，以便在Zend_Paginator_Adapter中使用它。工作查詢如下：

SELECT f.*, (SELECT (COUNT(p.post_id) - 1) 
FROM `forum_topic_posts` AS p WHERE f.topic_id = p.topic_id) AS post_count 
FROM `forum_topics` AS f WHERE f.forum_id = '2293' 
ORDER BY post_count DESC, last_update DESC 

所以我摸索出：

$subquery = $db->select() 
->from(array('p' => 'forum_topic_posts'), 'COUNT(*)') 
->where('p.topic_id = f.topic_id'); 

$this->sql = $db->select() 
->from(array('f' => 'forum_topics'), array('*', $subquery . ' as post_count')) 
->where('forum_id=?', $forumId, Zend_Db::PARAM_INT) 
->order('post_count ' . $orderDirection); 

但Zend公司與執行查詢時出現以下異常停止：

Zend_Db_Statement_Mysqli_Exception: Mysqli prepare error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT COUNT(*) FROM forum_topic_posts AS p WHERE (p.topic_id = f.to' at line 1

我怎麼能讓子查詢工作？

Answer 1

以下是使用Zend_Db OO接口編寫的查詢。

關鍵是大多使用一些Zend_Db_Expr對象作爲子查詢和COUNT函數。

$ss = $db->select() 
     ->from(array('p' => 'forum_topic_posts'), 
       new Zend_Db_Expr('COUNT(p.post_id) - 1')) 
     ->where('f.topic_id = p.topic_id'); 

$s = $db->select() 
     ->from(array('f' => 'forum_topics'), 
       array('f.*', 'post_count' => new Zend_Db_Expr('(' . $ss . ')'))) 
     ->where('f.forum_id = ?', 2293) 
     ->order('post_count DESC, last_update DESC'); 

echo $s; 
// SELECT `f`.*, SELECT COUNT(p.post_id) - 1 FROM `forum_topic_posts` AS `p` WHERE (f.topic_id = p.topic_id) AS `post_count` FROM `forum_topics` AS `f` WHERE (f.forum_id = 2293) ORDER BY `post_count DESC, last_update` DESC