mysql - 如果字段 "post_title"在另一行中重复，如何删除表行？

Question

Possible Duplicate:
Remove Duplicate Rows Leaving Oldest Row Only?

我有一个posts_table在我的数据库中.. 该 posts_table 具有字段 post_title , post_id ，(以及其他一些不重要的)。

如果 post_title 在另一行中重复，我需要删除其中一行。

示例:

posts_table
-------------------------------------------
post_id  | post_title
-------------------------------------------
501      |  Some post title here  
502      |  Another post title
503      |  A test post tile
504      |  Some post title here  (this is duplicated, i need to delete this row)
505      |  A different post title

通过下面的句子，我可以检查所有重复的 post_titles

SELECT    post_title, COUNT(post_title) AS dup_count
FROM      posts_table
GROUP BY  post_title
HAVING    (COUNT(post_title) > 1) 

问题是，如何删除具有重复 post_titles 的所有行？

最好、最快的查询是:

delete from posts_table where post_id in (
  select post_id from (
    select post_id from posts_table a group by post_title having count(post_title) > 1
  ) b
)

Answer 1

试试这个:

DELETE FROM Posts_Table 
WHERE Post_ID NOT IN    
    (
     SELECT a.Post_ID
     FROM
        (
         SELECT Post_Title, Post_ID 
         FROM Posts_Table 
         GROUP BY Post_Title
         ) a
    )