MySQL去重，一条SQL语句完美解决【去重留一】

此处以某消费记录表(consume_record)为例，SQL语句如下：

    DELETE consume_record
    FROM
        consume_record,
        (
            SELECT
                min(id) id,
                user_id,
                monetary,
                consume_time
            FROM
                consume_record
            GROUP BY
                user_id,
                monetary,
                consume_time
            HAVING
                count(*) > 1
        ) t2
    WHERE
        consume_record.user_id = t2.user_id
        and consume_record.monetary = t2.monetary
        and consume_record.consume_time  = t2.consume_time
    AND consume_record.id > t2.id;

SQL语句分析：

1、查询出重复记录形成一个集合（临时表t2），集合里是每种重复记录的最小ID

    (SELECT min(id) id, user_id, monetary, consume_time FROM consume_record GROUP BY user_id, monetary, consume_time HAVING count(*) > 1 ) t2

2、关联<判断重复基准的字段

    consume_record.user_id = t2.user_id and consume_record.monetary = t2.monetary and consume_record.consume_time  = t2.consume_time

3、根据条件，删除原表中id大于t2中id的记录

    DELETE consume_record FROM ... WHERE ... AND consume_record.id > t2.id;
   

测试效果：

 

图一为删除前总记录数45541，图二为删除操作、从45541条记录中删除2800条重复记录用时0.09秒，图三为删除后总记录数。贴上测试表，如有需要的小伙伴，下载导入即可进行测试。consume_record.sql