Question

我需要在以下查询中添加一个连接，该连接将messages_message表连接到messages_threads表，并从messages_messages中最新的行返回“body”和“time”字段，其中messages_message.threadid = messages_threads.id。

很抱歉这太令人困惑了，我不知道怎么说出来！这是我当前的查询 - 除了'body'和'time'字段之外，它正确地提取所有内容。

SELECT 
    messages_threads.id AS threadid, messages_threads.name AS recipientsname, 
    senderid, username AS sendername, pictures.url AS senderpicture
FROM 
    messages_recipients
    JOIN messages_threads 
        ON messages_threads.id = messages_recipients.threadid
    JOIN users 
        ON users.id = messages_threads.senderid
    JOIN pictures 
        ON messages_threads.senderid = pictures.userid 
        AND pictures.profile = 1
WHERE messages_recipients.userid = $userid

Answer 1

您可以添加messages_message表的子查询，该子查询将为每个线程返回1行。例如：

SELECT 
    messages_threads.id AS threadid, messages_threads.name AS recipientsname, 
    senderid, username AS sendername, pictures.url AS senderpicture
FROM 
    messages_recipients
    JOIN messages_threads ON messages_threads.id = messages_recipients.threadid
    JOIN users ON users.id = messages_threads.senderid
    JOIN pictures ON messages_threads.senderid = pictures.userid AND pictures.profile = 1
    JOIN ( SELECT threadid, MAX(id) AS postid FROM messages_message GROUP BY threadid ) t ON message_threads.id = t.threadid
    JOIN messages_message ON t.threadid = messages_message.threadid AND t.postid = messages_message.id
WHERE messages_recipients.userid = $userid

Answer 2

我认为你还需要按身体和时间分组...... 或者你可以更多地指定你的查询..

从MySQL返回最新消息？

2 个答案: