查询重复记录
select 字段名 from 表名 where 字段名 in (select 字段名 from 表名 group by 字段名 having count(1) >= 2
) ORDER BY 字段名
查询出所有重复记录并且删除多余的只保留一条
delete from 表名
where
重复字段名 in (SELECT a.重复字段名from(select 重复字段名
from 表名
group by 重复字段名 having count(1) > 1) a
)
and
id(只保留id最小的一个) not in (
SELECT b.id from(select min(id) as id
from 表名
group by 重复字段名 having count(1)>1) b
)