正确排序MySQL结果（可能需要子查询）

我想创建一个用户可以互相发送消息的消息系统。它应该像Facebook一样基于线程。因此，每个用户应该只与另一个用户在一个特定的消息线程中

所有消息的主要概述没有按我希望的那样工作。它只显示线程最早（第一个）的消息文本和日期，不按最新发送的消息排序

这是我的

SELECT

-语句，我想我需要一个子查询，让它按照最新的日期和文本进行排序，但我不熟悉，也不知道放在哪里以及如何排序

因此，基本上我只希望消息线程按照收到的最新消息进行排序，显示特定线程的最新文本和日期

    $menu = mysql_query("SELECT 
t.`id`, t.`creator_uid`,
c.`uid` AS content_uid, c.`text`, c.`date` AS content_date,
a.`status`, a.`date` AS assign_date,
CASE 
WHEN t.`creator_uid`='".sInput($_SESSION['uid'])."' THEN `receiver_uid`
WHEN t.`receiver_uid`='".sInput($_SESSION['uid'])."' THEN `creator_uid`
END AS uid
FROM `messages_content` c
LEFT JOIN `messages_thread` t ON t.`id` = c.`thread_id`
LEFT JOIN `messages_assign` a ON a.`id` = t.`id`
WHERE 
t.`creator_uid`='".sInput($_SESSION['uid'])."' 
OR 
t.`receiver_uid`='".sInput($_SESSION['uid'])."' 
GROUP BY t.`id` 
ORDER BY c.`id` DESC") or die (mysql_error());

---

MySQL数据库结构：

消息分配

：

id

，

uid

，

线程id

，

状态

，

日期

$menu = mysql_query("SELECT 
    t.`id`, t.`creator_uid`,
    c.`uid` AS content_uid, c.`text`, c.`date` AS content_date,
    a.`status`, a.`date` AS assign_date,
    CASE 
    WHEN t.`creator_uid`='".sInput($_SESSION['uid'])."' THEN `receiver_uid`
    WHEN t.`receiver_uid`='".sInput($_SESSION['uid'])."' THEN `creator_uid`
    END AS uid
FROM `messages_content` c
LEFT JOIN `messages_thread` t ON t.`id` = c.`thread_id`
LEFT JOIN `messages_assign` a ON a.`id` = t.`id`
LEFT JOIN (SELECT thread_id, MAX(date) AS latest_post_date
            FROM messages_contents
            GROUP BY thread_id) AS m ON t.id = m.thread_id
WHERE 
t.`creator_uid`='".sInput($_SESSION['uid'])."' 
OR 
t.`receiver_uid`='".sInput($_SESSION['uid'])."' 
GROUP BY t.`id` 
ORDER BY m.latest_post_date DESC") or die (mysql_error());

消息内容

：

id

，

uid

，

线程id

，

文本

，

日期

$menu = mysql_query("SELECT 
    t.`id`, t.`creator_uid`,
    c.`uid` AS content_uid, c.`text`, c.`date` AS content_date,
    a.`status`, a.`date` AS assign_date,
    CASE 
    WHEN t.`creator_uid`='".sInput($_SESSION['uid'])."' THEN `receiver_uid`
    WHEN t.`receiver_uid`='".sInput($_SESSION['uid'])."' THEN `creator_uid`
    END AS uid
FROM `messages_content` c
LEFT JOIN `messages_thread` t ON t.`id` = c.`thread_id`
LEFT JOIN `messages_assign` a ON a.`id` = t.`id`
LEFT JOIN (SELECT thread_id, MAX(date) AS latest_post_date
            FROM messages_contents
            GROUP BY thread_id) AS m ON t.id = m.thread_id
WHERE 
t.`creator_uid`='".sInput($_SESSION['uid'])."' 
OR 
t.`receiver_uid`='".sInput($_SESSION['uid'])."' 
GROUP BY t.`id` 
ORDER BY m.latest_post_date DESC") or die (mysql_error());

---

messages\u-thread

：

id

，

creator\u-uid

，

receiver\u-uid

，您需要加入一个子查询，该子查询可以：

SELECT select thread_id, MAX(date) as latest_post_date
FROM messages_contents
GROUP BY thread_id

然后按

latest\u post\u date

$menu = mysql_query("SELECT 
    t.`id`, t.`creator_uid`,
    c.`uid` AS content_uid, c.`text`, c.`date` AS content_date,
    a.`status`, a.`date` AS assign_date,
    CASE 
    WHEN t.`creator_uid`='".sInput($_SESSION['uid'])."' THEN `receiver_uid`
    WHEN t.`receiver_uid`='".sInput($_SESSION['uid'])."' THEN `creator_uid`
    END AS uid
FROM `messages_content` c
LEFT JOIN `messages_thread` t ON t.`id` = c.`thread_id`
LEFT JOIN `messages_assign` a ON a.`id` = t.`id`
LEFT JOIN (SELECT thread_id, MAX(date) AS latest_post_date
            FROM messages_contents
            GROUP BY thread_id) AS m ON t.id = m.thread_id
WHERE 
t.`creator_uid`='".sInput($_SESSION['uid'])."' 
OR 
t.`receiver_uid`='".sInput($_SESSION['uid'])."' 
GROUP BY t.`id` 
ORDER BY m.latest_post_date DESC") or die (mysql_error());

---

谢谢，它似乎可以正确地排序，但它不会显示消息线程的最新文本。我试图在子查询中添加

文本

，但是它根本没有显示任何文本。我是否需要另一个子查询以获取已发送的最新文本？我以为您只想在最新消息时间之前订购，而不是显示最新消息。有关如何获取整行的最新日期，请参见。