mysql - mysql查询中的重复列名错误

Question

如果来自我的查询并且不知道如何解决我的查询，我会收到重复列名的错误

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;    

任何人都可以帮忙吗

Answer 1

为避免重复使用其表为列名添加前缀，如下所示：

tab_name.col_name

Answer 2

尝试更换

WHERE senderid ='3' 
  OR recipientid='3' 

和

HAVING senderid ='3' 
  OR recipientid='3' 

快乐编码！

Answer 3

Answer 4

为了避免重复写入查询，如下使用前缀（tableName）.columnname：

select id, name1,name2 from(
select table1.id,table1.name as name1, table2.name as name2 from
table1
innerjoin table2 on table1.id=table2.table1_id
)group by id