从INNER JOIN中选择最后一条记录并进行分组 [英] Selecting last record from INNER JOIN and grouping

问题描述

好的，所以我有一个查询，该查询从按日期DESC排序的每个用户中选择1条消息，但为每个组选择第一条消息.我需要按日期从每个组(每个用户)中选择最后一条消息 这是我的查询:

Okay so I have a query that selects 1 message from each user that is ordered by date DESC but selects the first message for each group.. I need to select the last message by date from each group (each user) This is my query:

SELECT     people.id, 
           people.avatar, 
           people.firstname, 
           people.lastname, 
           LEFT(messages.message, 90) AS message, 
           messages.seen, 
           messages.date 
FROM       people 
INNER JOIN messages 
ON         people.id = messages.sender_id 
WHERE      reciever_id = '". $user_data['id'] ."' 
GROUP BY   sender_id 
ORDER BY   date DESC limit 11

推荐答案

请稍等一下，请原谅我的语法，但是我可能会尝试这样的方法.

Please excuse my syntax if it is a bit off, but I would probably try something like this.

SELECT people.id, 
       people.avatar, 
       people.firstname, 
       people.lastname, 
       LEFT(msg.message, 90) AS message, 
       msg.seen, 
       msg.date 
FROM  people 
INNER JOIN (SELECT message, seen, date, sender_id
                FROM messages GROUP By sender_id 
                ORDER By date DESC LIMIT 1) msg
                ON people.id = msg.sender_id
WHERE      reciever_id = '". $user_data['id'] ."' 

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