mysql删除表中重复数据，（只保留一行）

示例表中数据如下：

根据uniqle_id这一列来判断数据是否重复
1.查看重复的数据有哪些

select uniqle_id,name from person group by uniqle_id having count(uniqle_id) > 1

结果如下：

2.删除重复的列，只保留id最小的一行

delete from person where uniqle_id in (
select * from
(select min(uniqle_id) from person group by uniqle_id having count(uniqle_id) > 1) temp
)
and id not in 
(select * from 
(select min(id) from person group by uniqle_id having count(uniqle_id)> 1 )temp2
)

3.删除所有重复的行

delete from person where uniqle_id in (
select * from
(select min(uniqle_id)as uniqle_id from person group by uniqle_id having count(uniqle_id) > 1) temp
)

（sql中的temp存在的作用是给子查询的结果起一个别称，如果不起这个别称的话，会报错：SQL 错误 [1248] [42000]: Every derived table must have its own alias）