mysql删除重复数据，只保留一条

1. 分组查询，查到数据大于1的有哪些数据
2. 查这些重复数据最小的id是什么（如果没有这个，那此方法不适用）
3. 关联查询，条件是值相同，但是id大于最小id，最后在进行删除。

实际使用SQL如下：

SELECT vim_id, vim_name,count(*)
FROM ops_sys_vgw_info
group by vim_id,vim_name
having count(*) > 1;

SELECT vim_id, vim_name,min(id)
FROM ops_sys_vgw_info
group by vim_id,vim_name
having count(*) > 1;

DELETE a
FROM ops_sys_vgw_info a, (
		SELECT vim_id, vim_name, min(id) AS id
		FROM ops_sys_vgw_info
		GROUP BY vim_id, vim_name
		HAVING count(*) > 1
	) b
WHERE a.vim_id = b.vim_id
	AND a.id > b.id;

参考：https://blog.csdn.net/weixin_40052298/article/details/118415616