MYSQL 查询 : get the latest date with grouped by data

Question

我有一张聊天 table 。

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消息 I senderID I recipentID I date

我想通过对话获取最新消息组的查询。 (例如，如果 'senderID = 1 and the recipentID = 2' 与 'senderID = 2 and the recipentID = 1' 是同一个对话)

Answer 1

您可以在中使用。 MySQL 支持带有 in 的元组，所以这是一种方法:

select c.*
from chats c
where (least(senderID, recipentID), greatest(senderID, recipentID), date) in
       (select least(senderID, recipentID), greatest(senderID, recipentID), max(date)
        from chats c
        group by least(senderID, recipentID), greatest(senderID, recipentID)
       );