mysql删除重复行

为什么80%的码农都做不了架构师？>>>   

表relation

 create table  relation(
 id int primary key  auto_increment,
 userId int not null,
 fanId int not null
 );

插入几条数据

insert into relation(userId,fanId) 
values(1,1)  ,(1,1) ,(1,1), (2,2),(2,2) ,(3,3),(3,3);

表中的数据

id	userId	fanId
1	1	1
2	1	1
3	1	1
4	2	2
5	2	2
6	3	3
7	3	3

去重

delete t from relation s
join relation t using(userId,fanId)
where s.id<t.id;

 

 

转载于:https://my.oschina.net/yqz/blog/1837557