Question

我有一个小表（TABLEA），其中有两列IDA和DATETIMEA。

TABLEA

IDA  DATETIMEA
1    2020-03-16 13:15:00
2    2020-03-17 15:25:00
3    2020-03-18 17:10:00
5    2020-03-19 11:44:00
5    2020-03-20 12:55:00
5    2020-03-21 19:35:00
7    2020-03-22 10:13:00
8    2020-03-22 15:25:00
8    2020-03-28 12:12:00
9    2020-03-29 17:55:00
10   2020-03-30 11:54:00
12   2020-03-30 15:35:00
12   2020-03-31 13:19:00

我正在尝试获取每天IDA的总数，最近7天的总数以及最近30天的总数。

预期产量

DATE       DAY L7 L30
2020-03-16 1   1  1
2020-03-17 1   2  2
2020-03-18 1   3  3
2020-03-19 1   4  4
2020-03-20 1   5  5
2020-03-21 1   6  6
2020-03-22 2   8  8  
2020-03-28 1   3  9
2020-03-29 1   4  10
2020-03-30 2   6  12
2020-03-31 1   7  13

我尝试将与日期相关的输出放入子查询中，但它们返回0。

SELECT t.DATETIMEA::date date,
COUNT(t.*) "day",
(SELECT COUNT(w.*) FROM TABLEA w WHERE w.DATETIMEA::date BETWEEN w.DATETIMEA::date AND w.DATETIMEA::date - 7) week,
(SELECT COUNT(m.*) FROM TABLEA m WHERE m.DATETIMEA::date BETWEEN m.DATETIMEA::date AND m.DATETIMEA::date - 30) "month"
FROM TABLEA t
GROUP BY t.DATETIMEA::date
ORDER BY t.DATETIMEA::date

Answer 1

如果您的数据在几天内可能会出现间隔，则您需要一个range框架规范而不是一个rows框架。很高兴Postgres支持此规范，因此您可以执行以下操作：

select
    datetimea::date date,
    count(*) "day",
    sum(count(*)) over(
        order by datetimea::date
        range between '7 day' preceding and current row
    ) l7,
        sum(count(*)) over(
        order by datetimea::date
        range between '30 day' preceding and current row
    ) l30
from mytable
group by datetimea::date
order by datetimea::date

Demo on DB Fiddle ：

date       | day | l7 | l30
:--------- | --: | -: | --:
2020-03-16 |   1 |  1 |   1
2020-03-17 |   1 |  2 |   2
2020-03-18 |   1 |  3 |   3
2020-03-19 |   1 |  4 |   4
2020-03-20 |   1 |  5 |   5
2020-03-21 |   1 |  6 |   6
2020-03-22 |   2 |  8 |   8
2020-03-28 |   1 |  4 |   9
2020-03-29 |   1 |  4 |  10
2020-03-30 |   2 |  4 |  12
2020-03-31 |   1 |  5 |  13

Answer 2

我认为窗口函数可以满足您的要求：

select t.datetimea::date, count(*) as on_day,
       sum(count(*)) over (order by t.datetimea::date rows between 6 preceding and current row) as sum_7,
       sum(count(*)) over (order by t.datetimea::date rows between 29 preceding and current row) as sum_30
from tablea t
group by t.datetimea::date;

在“过去7天”中，我假设您的意思是今天和之前的6天。如果您指的是今天的7天，则可以轻松调整窗框。

PostgreSQL结合了一个计数，最近7天计数和最近30天计数按天分组

2 个答案: