delete from zqzrdp
where tel in (select min(dpxx_id) from zqzrdp group by tel having count(tel)>1);
运行，报错
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。
难倒仅仅能分步操作，蛋疼
下面是网友写的。相同是坑爹的代码，我机器上执行不了。
1. 查询须要删除的记录，会保留一条记录。
| 代码例如以下 | 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. 删除反复记录，仅仅保留一条记录。注意。subject,RECEIVER 要索引。否则会非常慢的。
| 代码例如以下 | 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. 查找表中多余的反复记录。反复记录是依据单个字段（peopleId）来推断
| 代码例如以下 | 复制代码 |
|
select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) |
|
4. 删除表中多余的反复记录，反复记录是依据单个字段（peopleId）来推断。仅仅留有rowid最小的记录
| 代码例如以下 | 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.删除表中多余的反复记录（多个字段）。仅仅留有rowid最小的记录
| 代码例如以下 | 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) |
|