mysql删除重复记录只保留一条（最简单）

查找出这三个字段重复的数据只保留一条，其余的全部删除

sql语句：

DELETE FROM jxkh_evaluation_detail WHERE id NOT IN (SELECT id from ( SELECT min(id) AS id FROM jxkh_evaluation_detail GROUP BY project_id, lib_item_id,obj_id)a)