题解 | 每天登陆最早的用户的内容喜好

select log_day,t2.user_id,hobby from
(
select * ,dense_rank()over(partition by log_day order by log_date) ranking from(
select user_id uid,left(log_time,10) log_day,right(log_time,8) log_date
from login_tb) as t1
join user_action_tb uat
on t1.uid = uat.user_id) as t2
where ranking = 1

1.把日期分开

2.进行排序

3.表连接

4.筛选排名为1的