mysql – 删除表中的重复条目

参见英文答案 > How to delete Duplicates in MySQL table                                    4个
我想删除下表中的多个重复键：

id | name   | uid
1  | ekta   | 5
2  | ekta   | 5
3  | sharma | 10
4  | sharma | 10

希望它像

id | name   | uid
1  | ekta   | 5
3  | sharma | 10

我正在使用mysql.可能吗？
我不能使用唯一约束查询来创建唯一的输入,因为我希望输入到表中的这些重复条目.

解决方法:

一种方法是使用LEFT JOIN在子查询上连接表.子查询获取每个UID的最低ID.当记录在子查询上没有匹配时,只表示它没有匹配的记录,可以安全删除.

DELETE  a
FROM    TableName a
        LEFT JOIN
        (
            SELECT  uid, MIN(ID) min_ID
            FROM    TableName
            GROUP   BY uid
        ) b ON  a.uid = b.uid AND
                a.ID = b.min_ID
WHERE   b.uid IS NULL

> SQLFiddle Demo

但是,如果UID的记录可以具有不同的名称,则需要在group by子句中包含name,否则将仅保留具有最低ID的唯一uid.

DELETE  a
FROM    TableName a
        LEFT JOIN
        (
            SELECT  uid, MIN(ID) min_ID, name
            FROM    TableName
            GROUP   BY uid, name
        ) b ON  a.uid = b.uid AND
                a.ID = b.min_ID AND
                a.name = b.name
WHERE   b.uid IS NULL

> SQLFiddle Demo
> SQLFiddle Demo (the same uid with different name)

标签：sql,mysql,sql-delete,stored-procedures
来源： https://codeday.me/bug/20190901/1780788.html