我在 PostgreSQL 10.5 中有一个表 trips
:
id start_date end_date
----------------------------
1 02/01/2019 02/03/2019
2 02/02/2019 02/03/2019
3 02/06/2019 02/07/2019
4 02/06/2019 02/14/2019
5 02/06/2019 02/06/2019
我想计算与给定周重叠的旅行天数。表中的行程具有包含范围。每周从星期一开始,到星期日结束。预期结果是:
week_of days_utilized
------------------------
01/28/19 5
02/04/19 8
02/11/19 4
日历引用:
Monday 01/28/19 - Sunday 02/03/19
Monday 02/04/19 - Sunday 02/10/19
Monday 02/11/19 - Sunday 02/17/19
我知道如何用我使用的编程语言编写此代码,但我更喜欢在 Postgres 中执行此操作,并且我不清楚从哪里开始......
最佳答案
您似乎想要generate_series()
和join
和group by
。要计算涵盖的周数:
select gs.wk, count(t.id) as num_trips
from generate_series('2019-01-28'::date, '2019-02-11'::date, interval '1 week') gs(wk) left join
trips t
on gs.wk <= t.end_date and
gs.wk + interval '6 day' >= t.start_date
group by gs.wk
order by gs.wk;
编辑:
我看到你想要覆盖这些日子。这在聚合中需要做更多的工作:
select gs.wk, count(t.id) as num_trips,
sum( 1 +
extract(day from (least(gs.wk + interval '6 day', t.end_date) - greatest(gs.wk, t.start_date)))
) as days_utilized
from generate_series('2019-01-28'::date, '2019-02-11'::date, interval '1 week') gs(wk) left join
trips t
on gs.wk <= t.end_date and
gs.wk + interval '6 day' >= t.start_date
group by gs.wk
order by gs.wk;
注意:这不会返回您所拥有的确切结果。我认为这些都是正确的。
关于sql - 从多个日期范围中提取每周的天数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55405882/