Sql 如何将这些查询转换为子查询？

如何将其转换为单个查询。我提出了以下质疑：

$msgs=mysql_query("select m.subject, m.msg from message as m, message_users as mu where m.id=mu.msg_id and mu.user_id=$u_id order by dateof_msg desc");
while($row1=mysql_fetch_array($msgs))
{
        $total_msg = $row1['msg'];
        $own_id = mysql_query("select owner_id from message where msg='$total_msg' ");
        while($o_id=mysql_fetch_array($own_id))
        {
            $owners_id = $o_id['owner_id'];
            $uname = mysql_query("select name from users where id='$owners_id'");

            while($username=mysql_fetch_array($uname))
            {
                $sen_name = $username['name'];
                echo $sen_name."&nbsp;&nbsp;".$owners_id."&nbsp;&nbsp;&nbsp;&nbsp;".$total_msg."<br />";
            }
        }
}

请尝试此查询

select m.subject, m.msg, m.owner_id, u.name 
from message as m, message_users as mu, users as u 
where m.id=mu.msg_id and mu.user_id=<userId> and msg=<MESSAGE> and u.id = mu.userId
order by dateof_msg desc

选择m.subject、m.msg、m.owner\u id、u.name
来自消息作为m，消息作为mu，用户作为u
其中m.id=mu.msg\u id和mu.user\u id=以及msg=和u.id=mu.userId
按日期订购信息说明

我已加入所有表，以便返回所有必需的字段

尝试此查询：

select m.subject, m.msg, m.owner_id, users.name 
from message as m, message_users as mu 
   inner join users on (message.owner_id =  users.id)
where m.id=mu.msg_id and mu.user_id=$u_id order by dateof_msg desc

如果你能告诉我你想做什么，我可以改进答案：message_用户和message表的结构是什么？为什么你想把它们都连接起来

编辑：这个怎么样

select m.id, m.subject, m.msg, owner.id, 
    owner.name, receivers.id, receivers.name
from message as m
    inner join message_users as mu on (m.id = mu.msg_id)
    inner join users as owner on (m.owner_id = owner.id)
    inner join users as receivers on (m.user_id = receivers.id)
where receivers.user_id=$u_id 
order by dateof_msg desc

---

问题是，对于每条消息和每个接收者，您将得到一行，但是使用PHP，您可以对信息进行分组（比循环中的3个查询更有效）

开发消息通信系统消息表，其中包含发送者信息和消息用户表，其中包含消息接收者。在这段代码中，您试图获取所有消息及其所有者，然后打印到列表中，不是吗？在这种情况下，您真的需要从消息用户处获取数据吗？如果这是您想要的，请将此答案标记为正确答案，因为查询不正确。把它放在：

$userlist=mysql\u query（“…”）或die（mysql\u error（））您将看到错误。
select m.id, m.subject, m.msg, owner.id, 
    owner.name, receivers.id, receivers.name
from message as m
    inner join message_users as mu on (m.id = mu.msg_id)
    inner join users as owner on (m.owner_id = owner.id)
    inner join users as receivers on (m.user_id = receivers.id)
where receivers.user_id=$u_id 
order by dateof_msg desc