mysql - 按发行日期累计计数

Question

我有一个表格，显示每个日期的客户 ID 列表 - 显示在任何特定日期活跃的客户。因此每个日期都可以包含在另一个日期中也存在的 ID。

bdate            customer_id
2012-01-12       111
2012-01-13       222
2012-01-13       333
2012-01-14       111
2012-01-14       333
2012-01-14       666
2012-01-14       777

我想编写一个查询来计算两个日期之间唯一 ID 的总数 - 开始日期是行日期，结束日期是 future 的特定日期。

我的查询是这样的:

select
  bdate,
  count(distinct customer_id) as cts
from users
where bdate between bdate and current_date
group by 1
order by 1

但这会产生每个日期的唯一用户数，如下所示:

bdate            customer_id
2012-01-12       1
2012-01-13       2
2012-01-14       4

我想要的结果是(开始行日期和 2012-01-14 之间的用户数)

bdate            customer_id
2012-01-12       5  - includes (111,222,333,666,777)
2012-01-13       5  - includes (222,333,111,666,777)
2012-01-14       4  - includes (111,333,666,777)

Answer 1

赞@Strawberry说，你可以像这样加入:

select
    t1.bdate,
    count(distinct t2.customer_id) as cts
from users t1
join users t2 on t2.bdate >= t1.bdate
where t1.bdate between t1.bdate and current_date
group by t1.bdate
order by t1.bdate

加入 t2 可以获得特定日期和 current_date 之间的所有用户，然后 count t2 的 customer_id，就是这样。

SqlFiddle Demo Here