MySQL数据库定时任务，在一个表中，每1小时定时删除每个用户较早的数据，只保留最新的10条记录

Question

数据库表详情看附图，表中存储多个用户的记录，search_time表示该条记录插入数据库的时间

Answer 1

写个脚本 用crontab设置每小时执行一次，SQL语句如下：
delete from tbname order by search_time desc limit 11,1000
如果数据超过1000可以再大点。追问

你说的是一个用户的情况，这个表是保存了多个用户的记录，我不知道怎么实现对应的每个用户删除较早的记录，只保留最新10条

追答

试试 

delete from tbname where id not in (select id 
from tbname as a1  
     inner join (select a.u_id 
                 from article as a  
                      left join article as b  
                        on a.u_id = b.u_id  
                           and a.search_time <= b.search_time  
                 group by a.u_id,a.search_time 
                 having count(b.search_time) <= 10 
    ) as b1 on a1.u_id = b1.u_id and a1.search_time = b1.search_time 
order by a1.u_id,a1.search_time desc
)

追问

运行不了

追答

delete from tbname where id not in (select id
from tbname as a1
inner join (select a.u_id,a.search_time
from article as a
left join article as b
on a.u_id = b.u_id
and a.search_time <= b.search_time
group by a.u_id,a.search_time
having count(b.search_time) <= 10
) as b1 on a1.u_id = b1.u_id and a1.search_time = b1.search_time
order by a1.u_id,a1.search_time desc
)

追问

参考你的答案我做出来了，谢谢你