mysql之删除 mySQL 5.7.9 中的所有重复行

我有这样的 table

 select id,channel,post from posts limit 10 
+------+------------+-------+ 
| id   | channel    | post  | 
+------+------------+-------+ 
| 1433 | channel2   | 19353 | 
| 1434 | channel2   | 19353 | 
| 1435 | channel2   | 19354 | 
| 1436 | channel2   | 19354 | 
| 1437 | channel2   | 19356 | 
| 1438 | channel2   | 19357 | 
| 1439 | channel2   | 19358 | 
| 1440 | channel2   | 19359 | 
| 1441 | channel2   | 19360 | 
| 1634 | channel2   | 19360 | 
+------+------------+-------+ 

在那个表 id是 primary key ，现在在那个表中我有一个 channel 的重复帖子，我尝试添加一个 unique key使用此查询表并删除所有重复行

ALTER ignore TABLE `posts` ADD UNIQUE key `unique_index` (`channel`, `post`); 

但在 mysql 5.7.9我们不能那样做!

所以我想知道如何删除重复行并为 channel 添加唯一键, post
解决方案

    DELETE FROM posts 
WHERE ID Not in (SELECT*  
                 FROM (SELECT MIN(ID) 
                       FROM posts  
                       GROUP BY channel, Post) B 
                )  

请您参考如下方法:

您不能在删除的子查询中使用同一个表。
所以你需要使用额外的交付表来解决这个问题。

DELETE FROM 
 posts  
WHERE 
 posts.id NOT IN (   
  SELECT  
   id 
  FROM (     
    SELECT  
      MIN(id) AS id 
    FROM 
      posts  
    GROUP BY 
      posts.channel 
    , posts.post 
  )  
   AS  
    posts_id     
)