为什么条目不被删除？

-1

为什么MySQL没有通过这个查询删除条目？为什么条目不被删除？

DELETE FROM transport_cms.page WHERE Id IN (SELECT * FROM (SELECT g.Id FROM transport_cms.page g, transport_cms.page p where g.Url = p.Url and g.Site_id = p.Site_id and g.Id != p.Id group by p.Site_id) AS p);

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2017-05-12 destroyer25t

是什么告诉你的原因是什么？你只需要首先运行'SET SQL_SAFE_UPDATES = 0;'然后用子查询等来运行你的delete语句？ –

您查询不正确。提供适当的问题来解决问题 –

我想删除表transport_cms.page中的dublicate条目。 Dublicate - 当Url字段相同时，Site_id字段相等，但Id不相等。 – destroyer25t

SELECT g.Id FROM transport_cms.page g, transport_cms.page p where g.Url = p.Url and g.Site_id = p.Site_id and g.Id != p.Id group by p.Site_id

这个脚本是无效的。 select不能包含不在group中的字段。

来源

2017-05-12 04:31:33

您的查询字词部分工作： -

drop table if exists transport_cms_page; 

create table transport_cms_page (id int,url varchar(3),site_id int); 

insert into transport_cms_page values 
(1,'aaa',1),(2,'aaa',1), (3,'aaa',1); 

MariaDB [sandbox]> DELETE FROM transport_cms_page 
    -> WHERE Id IN (
    -> SELECT * FROM (
    -> SELECT g.Id 
    -> FROM transport_cms_page g, transport_cms_page p 
    -> where g.Url = p.Url and g.Site_id = p.Site_id and p.Id <> g.Id 
    -> group by p.Site_id 
    ->) AS p 
    ->); 
Query OK, 1 row affected (0.03 sec) 

MariaDB [sandbox]> 
MariaDB [sandbox]> select * from transport_cms_page; 
+------+------+---------+ 
| id | url | site_id | 
+------+------+---------+ 
| 1 | aaa |  1 | 
| 3 | aaa |  1 | 
+------+------+---------+ 
2 rows in set (0.00 sec)

当您运行查询，这可能是更适合

MariaDB [sandbox]> DELETE FROM transport_cms_page 
    -> WHERE Id not IN 
    -> (
    -> select minid 
    -> from 
    -> (select url,site_id, min(id) minid 
    -> from transport_cms_page 
    -> group by url,site_id 
    ->) m 
    ->); 
Query OK, 2 rows affected (0.02 sec) 

MariaDB [sandbox]> 
MariaDB [sandbox]> 
MariaDB [sandbox]> select * from transport_cms_page; 
+------+------+---------+ 
| id | url | site_id | 
+------+------+---------+ 
| 1 | aaa |  1 | 
+------+------+---------+ 
1 row in set (0.00 sec)

来源

2017-05-12 07:35:12

为什么条目不被删除？

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