按月获取活跃用户答案

【问题标题】：Get active users by month按月获取活跃用户
【发布时间】：2021-02-21 19:02:35
【问题描述】：

使用 MySQL，我试图获取我在任何给定月份的活跃用户数。我有一个包含ActivationDate 和TerminationDate 列的表，如果计算的月份在ActivationDate 和TerminationDate 之后为空，则用户处于活动状态并且应该被计算在内。我想按月总结这些金额。我想我可以只sum 每边计算总数，但分解它不会给我一个运行总数。我尝试过使用窗口函数，但我没有足够的经验来确切地知道我做错了什么，而且我不确定如何提出正确的问题。

例如，如果我有以下数据...

UserId  ActivationDate  TerminationDate
1  2020-01-01  null
2  2020-01-15  null
3  2020-01-20  2020-01-30
4  2020-02-01  null
5  2020-02-14  2020-02-27
6  2020-02-15  2020-02-28
7  2020-03-02  null
8  2020-03-05  null
9  2020-03-20  2020-03-21

我希望我的结果类似于：

2020-01  2  (there are 2 active users, since one signed up but cancelled before the end of the month)
2020-02  3  (2 from the previous month, plus 1 that signed up this month and is still active)
2020-03  5  (3 from previous, 2 new, 1 cancellation)

【问题讨论】：

标签： mysql sql datetime count window-functions

【解决方案1】：

您可以取消透视，然后汇总和求和。在 MySQL 8.0.14 或更高版本中，您可以使用横向连接：

select date_format(x.dt, '%Y-%m-01') as dt_month, 
    sum(sum(cnt)) over(order by date_format(x.dt, '%Y-%m-01')) as cnt_active_users
from mytable t
cross join lateral (
    select t.activationdate as dt, 1 as cnt
    union all select t.terminationdate, -1
) x
where x.dt is not null
group by dt_month
order by dt_month

在早期的 8.x 版本中：

select date_format(x.dt, '%Y-%m-01') as dt_month, 
    sum(sum(cnt)) over(order by date_format(x.dt, '%Y-%m-01')) as cnt_active_users
from (
    select activationdate as dt, 1 as cnt from from mytable
    union all select terminationdate, -1 from mytable 
) x
where x.dt is not null
group by dt_month
order by dt_month

【讨论】：

不错的一个！感谢那。我会尝试并由我的团队运行它。如果这是我们的答案，我一定会将其标记为已解决。

【解决方案2】：

你没有说什么版本的 MySQL。如果您使用的是 8.0，这应该可以工作：

create table userdates (
    UserId int not null,
    ActivationDate date not null,
    TerminationDate date null
);

insert into userdates (UserId, ActivationDate, TerminationDate)
values
  (1, cast("2020-01-01" as date), null      )
, (2, cast("2020-01-15" as date), null      )
, (3, cast("2020-01-20" as date), cast("2020-01-30" as date))
, (4, cast("2020-02-01" as date), null      )
, (5, cast("2020-02-14" as date), cast("2020-02-27" as date))
, (6, cast("2020-02-15" as date), cast("2020-02-28" as date))
, (7,  cast("2020-03-02" as date), null     )
, (8,  cast("2020-03-05" as date), null     )
, (9,  cast("2020-03-20" as date), cast("2020-03-21" as date))
, (10, cast("2020-07-20" as date), null)
, (11, cast("2019-09-12" as date), cast("2019-09-14" as date));

WITH RECURSIVE d (dt) 
AS (
      SELECT cast("2019-01-01" as date)
      UNION ALL
      SELECT date_add(dt, interval 1 month)
      FROM d 
      WHERE dt < cast("2020-12-01" as date)
    )

select d.dt
, count(distinct ud.UserId) as UserCount
from userdates ud
  right outer join d on d.dt >= date_format(ud.ActivationDate, '%Y-%m-01')
              and (d.dt <= ud.TerminationDate or ud.TerminationDate is null)
group by d.dt;

【讨论】：