mysql删除重复记录（去重）

DELETE consum_record FROM  consum_record,  (   SELECT    min(id) id,    user_id,    monetary,    consume_time   FROM    consum_record   GROUP BY    user_id,    monetary,    consume_time   HAVING    count(*) > 1  ) t2 WHERE  consum_record.user_id = t2.user_id  and consum_record.monetary = t2.monetary  and consum_record.consume_time = t2.consume_time AND consum_record.id > t2.id;

上面这条sql语句，分为3步来理解：

(1)查询出重复记录形成一个集合（临时表t2），集合里是每种重复记录的最小ID

(SELECT min(id) id, user_id, monetary, consume_time FROM consum_record GROUP BY user_id, monetary, consume_time HAVING count(*) > 1 ) t2 

(2)关联 判断重复基准的字段

consum_record.user_id = t2.user_id and consum_record.monetary = t2.monetary and consum_record.consume_time = t2.consume_time 

(3)删除原表中id大于t2中id的记录