mysql - mysql查询中的重复列名错误

Question

如果从我的查询中得到重复列名的错误并且不知道如何解决我的查询是

SELECT distinct(courseid+senderid+recipientid) as diskey,
       mess.id,
       User.firstName as recipientName,
       Course.name,
       senderid,
       recipientid,
       courseid,
       message,
       mess.status,
       mess.createdOn 
FROM 
(
    SELECT * 
    from Message,User,Course 
    where Message.recipientid=User.id 
        and Message.courseid=Course.id 
    order by Message.createdOn DESC
) as mess,
     User,
     Course 
WHERE senderid ='3' 
      OR recipientid='3' 
GROUP BY diskey;    

谁能帮上忙

Answer 1

为避免重复，在列名前加上其表的前缀，如下所示:

tab_name.col_name