MySQL 数据库模式，用于一对一的简单聊天

Question

我尝试使用这些架构进行简单的聊天：

mes_id  int(10) unsigned Auto Increment  
mes_useid_receiver  int(10) unsigned     
mes_useid_sender    int(10) unsigned     
mes_date    int(10) unsigned     
mes_message text     
mes_read    tinyint(3) unsigned [0]  
mes_visible_for_who int(10) unsigned NULL   NULL = both; 0 = none; ID user

问题是，如何获取已接收消息和已发送消息的联系人列表？

我正在尝试这样的事情：

SELECT use_name, MAX(mes_date) AS date 
FROM message JOIN user ON mes_useid_receiver=use_id 
WHERE uti_id!=1 
AND (mes_useid_receiver=1 OR mes_useid_sender=1) 
AND (mes_visible_for_who IS NULL OR mes_visible_for_who=1) 
GROUP BY use_id 
ORDER BY date DESC

但是通过这个查询，我只能获取向 user_id = 1 发送消息的联系人，我还想获取 user_id = 1 发送消息的联系人。

已编辑：

通过联合，我几乎可以得到我想要的：

SELECT use_id, use_name, mes_read FROM message
JOIN user ON mes_useid_receiver=use_id
WHERE use_id!=1 
AND (mes_useid_receiver=1 OR mes_useid_sender=1) 
AND (mes_visible_for_who IS NULL OR mes_visible_for_who=1) GROUP BY use_id

UNION

SELECT use_id, use_name, mes_read FROM message
JOIN user ON mes_useid_sender=use_id
WHERE use_id!=1 
AND (mes_useid_receiver=1 OR mes_useid_sender=1) 
AND (mes_visible_for_who IS NULL OR mes_visible_for_who=1) GROUP BY use_id

我需要 mes_date 来排序列表，但如果我选择 mes_date 我会得到重复的行。

感谢您的帮助。

Answer 1

如果你要进入这个根目录，那么我的建议如下：

SELECT *  FROM(

    (SELECT use_id, use_name, mes_read ,mes_date FROM message
    JOIN user ON mes_useid_receiver=use_id
    WHERE use_id!=1 
    AND (mes_useid_receiver=1 OR mes_useid_sender=1) 
    AND (mes_visible_for_who IS NULL OR mes_visible_for_who=1)) GROUP BY use_id 

    UNION

    (SELECT use_id, use_name, mes_read ,mes_date FROM message
    JOIN user ON mes_useid_sender=use_id
    WHERE use_id!=1 
    AND (mes_useid_receiver=1 OR mes_useid_sender=1) 
    AND (mes_visible_for_who IS NULL OR mes_visible_for_who=1)) GROUP BY use_id 

) as d Order By mes_date desc

还看看你是否可以避免在每个选择中分组（你会觉得表现不佳）

问候