Question

可能重复：
Remove Duplicate Rows Leaving Oldest Row Only?

我的数据库中有posts_table .. posts_table包含字段post_title，post_id，（以及其他一些不重要的字段）。

如果post_title在另一行重复，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

使用下面的句子，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，如何删除所有具有重复post_titles的行？

最好和最快的查询是：

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
    )

如果字段“post_title”在另一行中重复，如何删除表行？

1 个答案: