我有这个事件表
+--------------+------------------+
| Field | Type |
+--------------+------------------+
| id | int(11) unsigned |
| start_date | timestamp |
| end_date | timestamp |
| ... | |
+--------------+------------------+
我需要一个 View ,将这些事件按开始日期按天分组,但如果结束日期与开始日期不在同一天, View 将再次包含该条目,但开始日期设置为 00:00第二天..(依此类推,根据需要重复多次,直到 start_date 与 end_date 在同一天)
举个例子:
如果事件表包含:
+--------------+----------------------------+----------------------------+
| id | start_date | end_date |
+--------------+----------------------------+----------------------------+
| 1 | 2014-12-02 14:12:00+00 | 2014-12-03 06:45:00+00 |
| 2 | 2014-12-05 15:25:00+00 | 2014-12-05 07:29:00+00 |
+--------------+----------------------------+----------------------------+
View 应包含:
+--------------+----------------------------+----------------------------+
| activity_id | start_date | end_date |
+--------------+----------------------------+----------------------------+
| 1 | 2014-12-02 14:12:00+00 | 2014-12-02 23:59:59+00 |
| 1 | 2014-12-03 00:00:00+00 | 2014-12-03 06:45:00+00 |
| 2 | 2014-12-05 15:25:00+00 | 2014-12-05 07:29:00+00 |
+--------------+----------------------------+----------------------------+
如有任何帮助,我们将不胜感激!
PS:我用的是postgresql
最佳答案
要获得所需的行,首先使用 set returning function连同 lateral join .从那里,使用 CASE
语句和 date arithmetics提取相关值。
这是一个让您入门的示例:
with data as (
select id, start_date, end_date
from (values
(1, '2014-12-02 14:12:00+00'::timestamptz, '2014-12-03 06:45:00+00'::timestamptz),
(2, '2014-12-05 15:25:00+00'::timestamptz, '2014-12-05 07:29:00+00'::timestamptz)
) as rows (id, start_date, end_date)
)
select data.id,
case days.d = date_trunc('day', data.start_date)
when true then data.start_date
else days.d
end as start_date,
case days.d = date_trunc('day', data.end_date)
when true then data.end_date
else days.d + interval '1 day' - interval '1 sec'
end as end_date
from data
join generate_series(
date_trunc('day', data.start_date),
date_trunc('day', data.end_date),
'1 day'
) as days (d)
on days.d >= date_trunc('day', data.start_date)
and days.d <= date_trunc('day', data.end_date)
id | start_date | end_date
----+------------------------+------------------------
1 | 2014-12-02 15:12:00+01 | 2014-12-02 23:59:59+01
1 | 2014-12-03 00:00:00+01 | 2014-12-03 07:45:00+01
2 | 2014-12-05 16:25:00+01 | 2014-12-05 08:29:00+01
(3 rows)
顺便说一句,根据您的操作,使用 date range 可能更有意义:
with data as (
select id, start_date, end_date
from (values
(1, '2014-12-02 14:12:00+00'::timestamptz, '2014-12-03 06:45:00+00'::timestamptz),
(2, '2014-12-05 07:25:00+00'::timestamptz, '2014-12-05 15:29:00+00'::timestamptz)
) as rows (id, start_date, end_date)
)
select data.id,
tstzrange(data.start_date, data.end_date)
from data;
id | tstzrange
----+-----------------------------------------------------
1 | ["2014-12-02 15:12:00+01","2014-12-03 07:45:00+01")
2 | ["2014-12-05 08:25:00+01","2014-12-05 16:29:00+01")
(2 rows)
关于SQL/Postgres 日期时间划分/规范化,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27398934/