mysql - 选择用户每周至少出现一次，持续数周

Question

假设您有一个如下所示的简单表格:

+---------+---------------------+
| user_id | activity_date       |
+---------+---------------------+
|   23672 | 2011-04-26 14:53:02 |
|   15021 | 2011-04-26 14:52:20 |
|   15021 | 2011-04-26 14:52:09 |
|   15021 | 2011-04-26 14:51:51 |
|   15021 | 2011-04-26 14:51:38 |
|    6241 | 2011-04-26 14:51:12 |
|     168 | 2011-04-26 14:51:12 |
...

如何选择过去 4 周内每周至少出现一次的 user_id 集？

Answer 1

select user_id, 
sum(if(activity_date between now() - interval 1 week and now(),1,0)) as this_week,
sum(if(activity_date between now() - interval 2 week and now() - interval 1 week,1,0)) as last_week,
sum(if(activity_date between now() - interval 3 week and now() - interval 2 week,1,0)) as two_week_ago,
sum(if(activity_date between now() - interval 4 week and now() - interval 3 week,1,0)) as three_week_ago
from activities
where activity_date >= now() - interval 4 week 
group by user_id
having this_week > 0 and last_week > 0 and two_week_ago > 0 and three_week_ago > 0