在MySQL中連接兩個表兩次。可能與否？

Question

的表用戶表結構，消息像風箱，

Users - ID, Name 

Messages - ID, Sender, Receiver, Message 

我要加入兩個表兩次狀結合與users.id的messages.sender與users.id messages.receiver。

是否有可能在一個單一的查詢來獲取與發送者的ID，發件人的姓名，接收器的ID，收件人姓名，郵件...（等）的結果 ??? ...

Answer 1

是的，你可以通過命名內做加盟：

select id, s.Name, r.Name from Messages 
    inner join users as s on (message.sender = s.id) 
    inner join users as r on (merssage.receiver = r.id) 

Answer 2

是的，你可根據需要多次加入表格。

SELECT 
    sender.ID AS `sender_id`, 
    sender.Name AS `sender_name`, 
    receiver.ID AS `receiver_id`, 
    receiver.Name AS `receiver_name`, 
    Messages.Message 
FROM 
    Messages 
INNER JOIN 
    Users AS sender 
ON 
    sender.ID = Messages.Sender 
INNER JOIN 
    Users AS receiver 
ON 
    receiver.ID = Messages.Receiver