mysql：按用户获取最后的会话记录

Question

我需要通过to_user以降序获取最后的会话记录。 我有一个叫做消息的表。请看下面的截图：

我希望以下列方式输出：

 from_user| to_user | message         | 
  241     |  226    |   How are you?  |
  241     |  256    | Hi test message |

我试过这个问题：

SELECT * FROM `messages` where from_user=241 group by to_user order by created DESC

我收到以下输出错误：

提前致谢。

Answer 1

试试他的：

SELECT t1.* 
FROM `messages` AS t1
JOIN (
   SELECT to_user, MAX(created) AS created
   FROM `messages` 
   WHERE from_user=241
   GROUP BY to_user
) AS t2 ON t1.to_user = t2.to_user AND t1.created = t2.created
WHERE from_user=241
ORDER BY t1.created DESC

Answer 2

SELECT *
FROM
  (SELECT *
   FROM `messages`
   WHERE from_user=241
   ORDER BY created DESC) as test
GROUP BY to_user

Answer 3

试试这个

SELECT * FROM `messages` where from_user=241 group by to_user order by id , created DESC

Answer 4

如果你想在一个字段中发布from_user的所有帖子（误解了我认为的问题）：

SELECT group_concat(messages.message) 
    FROM messages 
    WHERE from_user = 241 
    GROUP BY to_user 
    ORDER BY MAX(id) DESC

您必须说明您希望订购哪种标准。您可以开始对话或对话的最后一条消息。