Question

我正在寻找有关特殊用户事件的数据库。如果PID和UID整体相同，则必须清除表中的数据库整体。我的服务器安装了mysql 5.x，因此CET / Over（）分析功能无法正常工作。

我们非常感谢您的帮助。

Table 

ID  PID  UID
1    1    1
2    1    1
3    1    1
4    1    1
5    3    2
6    2    5

清理后所需的表

ID  PID  UID
1    1    1
5    3    2
6    2    5

Answer 1

您可以将delete与join一起使用。如果要为所有重复的对保留一行：

delete t
    from t join
         (select pid, uid, min(id) as min_id, count(*) as cnt
          from t
          group by pid, uid
         ) tt
         on tt.pid = t.pid and t.uid = tt.uid
    where t.id <> tt.min_id;

如果要删除所有个重复项，请将where更改为：

   where cnt >= 2

Answer 2

尝试如下

DELETE n1 FROM table n1 join
table n2 on n1.id > n2.id AND n1.PID = n2.PID and n1.UID=n2.UID

Answer 3

使用自我加入：

delete t 
from tablename t inner join tablename tt
on tt.pid = t.pid and tt.uid = t.uid 
where tt.id < t.id

请参见demo。
结果：

| id  | pid | uid |
| --- | --- | --- |
| 1   | 1   | 1   |
| 5   | 3   | 2   |
| 6   | 2   | 5   |

如何从mysql 5.0删除或删除重复的整体

3 个答案: