Cakephp在find方法中使用group by

Question

我正在尝试在我的关系数据库的find方法中使用Group by我希望从user_id过滤的结果集中获取具有唯一receiver_id的最新记录，以下是我的代码：

$this->loadModel('Chat');
        $lastChat = $this->Chat->find('all', array(
            'conditions' => array(
                'Chat.user_id' => $user_id['User']['id']
            ),
            'fields' => array(
                'Chat.id',
                'Chat.chat',
                'Chat.user_id',
                'Chat.receiver_id',
                'Chat.read',
                'Chat.created'
            ),
            'group' => array('Chat.receiver_id'),
            'order' => array('Chat.created DESC')
        ));

但是，这似乎不起作用。我不知道为什么，但我只得到一个结果...

如何根据上述规则获得多个结果。

Answer 1

尝试以下方法：

$db = $this->Chat->getDataSource();
$chats = $db->query("SELECT * , (Chat.user_id + Chat.receiver_id) AS dist
    FROM (
        SELECT *
        FROM  chats t
        WHERE ( t.user_id =$id OR t.receiver_id =$id )
        ORDER BY t.id DESC
    ) Chat
    GROUP BY dist
    ORDER BY Chat.id DESC");