Question

我是SQL新手，我需要每7天找一次count个用户。从2015年4月到现在，我每天都有一个用户表：

...
2015-05-16 00:00
2015-05-16 00:00
2015-05-17 00:00
2015-05-17 00:00
2015-05-17 00:00
2015-05-17 00:00
2015-05-17 00:00
2015-05-18 00:00
2015-05-18 00:00
...

我需要每7天计算一次用户数（每周），所以我每周都有数据。

SELECT COUNT(user_id), Activity_Date FROM TABLE_NAME

我需要这样的输出：

TotalUsers   week1  week2 week3 ..........and so on
  82              80     14    16

我使用DB Visualizer查询Oracle数据库。

Answer 1

你应该尝试以下，

Select 
  sum(Week1) + sum(Week2) + sum(Week3) + sum(Week4) + sum(Week5) as Total,
  sum(Week1) as Week1,
  sum(Week2) as Week2,
  sum(Week3) as Week3,
  sum(Week4) as Week4,
  sum(Week5) as Week5
From (
  select 
    case when week = 1 then 1 else 0 end as Week1,
    case when week = 2 then 1 else 0 end as Week2,
    case when week = 3 then 1 else 0 end as Week3,
    case when week = 4 then 1 else 0 end as Week4,
    case when week = 5 then 1 else 0 end as Week5
  from 
  (
      Select
        CEILING(datepart(dd,visitdate)/7+1) week,
        user_id
      from visitor
  )T
)D

这是Fiddle

你需要添加月份和时间结果也是如此。

Answer 2

SELECT COUNT(user_id), Activity_Date FROM TABLE_NAME WHERE Activity_Date > '2015-06-31';

这将获得过去7天的用户数量。

Answer 3

您如何定义周？这是SQL Server的一种方法，它相对于4月初开始每个七天的块。表达式将根据您的具体需求而有所不同：

select
    dateadd(
        dd,
        datediff(dd, cast('20150401' as date), Activity_Date) / 7 * 7,
        cast('20150401' as date)
    ) as WeekStart,
    count(*)
from T
group by datediff(dd, cast('20150401' as date), Activity_Date) / 7

甲骨文：

select
    trunc(Activity_date, 'DAY') as WeekStart,
    count(*)
from T
group by trunc(Activity_date, 'DAY') /* D and DAY are the same thing */

Answer 4

这是我的测试表：

user_id  act_date
1   01/04/2015
2   01/04/2015
3   04/04/2015
4   05/04/2015
..

这是我的疑问：

select week_offset, count(*) nb from (
select trunc((act_date-to_date('01042015','DDMMYYYY'))/7) as week_offset from test_date)
group by week_offset
order by 1

这是输出：

week_offset  nb
0   6
1   3
4   5
5   7
6   3
7   1
18  1

周抵消是从2015年4月1日起的一周中的数字，我们可以显示一周的第一天。有关实时测试，请参阅here。

SQL每7天计算一次用户数

4 个答案: