MySQL 删除数据库中重复数据（以部分数据为准）

时间：2021-06-06 22:15:58
delete from zqzrdp 

where tel  in (select min(dpxx_id) from  zqzrdp  group by tel  having count(tel)>1);

执行，报错MySQL 删除数据库中重复数据（以部分数据为准）


异常意为：你不能指定目标表的更新在FROM子句。傻了，MySQL 这样写，不行，让人郁闷。

难倒只能分步操作，蛋疼

以下是网友写的，同样是坑爹的代码，我机器上运行不了。

1. 查询需要删除的记录，会保留一条记录。

 代码如下 复制代码

select a.id,a.subject,a.RECEIVER from test1 a left join (select c.subject,c.RECEIVER ,max(c.id) as  bid from test1 c where status=0 GROUP BY RECEIVER,SUBJECT having count(1) >1) b on a.id< b.bid where  a.subject=b.subject and a.RECEIVER = b.RECEIVER and a.id < b.bid

2. 删除重复记录，只保留一条记录。注意，subject,RECEIVER 要索引，否则会很慢的。

 代码如下 复制代码

delete a from test1 a, (select c.subject,c.RECEIVER ,max(c.id) as  bid from test1 c where status=0 GROUP BY RECEIVER,SUBJECT having count(1) >1) b where a.subject=b.subject and a.RECEIVER = b.RECEIVER and a.id < b.bid;


3. 查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断

 代码如下 复制代码

select * from people
where peopleId in (select  peopleId  from  people  group  by  peopleId  having  count(peopleId) > 1)


4. 删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录

 代码如下 复制代码

delete from people 
where peopleId  in (select  peopleId  from people  group  by  peopleId   having  count(peopleId) > 1)
and rowid not in (select min(rowid) from  people  group by peopleId  having count(peopleId )>1)

5.删除表中多余的重复记录（多个字段），只留有rowid最小的记录

 代码如下 复制代码
delete from vitae a
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

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