计算 Postgresql 中的每日中断

Question

例如，我有中断开始日期时间：'2017-09-09 06:56:22' 和结束日期时间：'2017-09-13 14:22:45'。现在我想每天获取停电持续时间，如果整个停电然后给我'24:00:00'但是如果一天中只有一部分停电然后我们做减法ex：startTime - DayEndTime（StartTime）那个00:00:00 开始日结束。因此，如果一整天都停电，那么每天都会计算出来 24:00:00.

我如何在 postgresql 中解决这个问题？请帮忙

见下文table

StartTime   EndTime OutageTime

2017-09-09 6:56:32  2017-09-10 0:00:00  17:03:28
2017-09-10 0:00:00  2017-09-11 0:00:00  24:00:00
2017-09-11 0:00:00  2017-09-12 0:00:00  24:00:00
2017-09-12 0:00:00  2017-09-13 0:00:00  24:00:00
2017-09-13 0:00:00  2017-09-13 14:22:45 14:22:45

Answer 1

你可以只计算差值，只要是一整天就用24:00:00代替：

SELECT starttime,
       endtime,
       CASE endtime - starttime
          WHEN INTERVAL '1 day'
          THEN '24:00:00'
          WHEN INTERVAL '1 day 1 hour'
          THEN '25:00:00'
          ELSE CAST(endtime - starttime AS text)
       END AS outagetime
FROM outages;

Answer 2

您可以使用 generate_series() 执行此操作。以下是每天获取结果的逻辑：

select (case when date_trunc('day', g.dte) = date_trunc('day', o.start_time)
             then g.dte
             else date_trunc('day', g.dte)
        end),
       (case when date_trunc('day', g.dte) < date_trunc('day', o.end_time)
             then date_trunc('day', g.dte) + interval '1 day'
             else o.end_time
        end)
from outages o, lateral 
     generate_series(start_time, end_time, interval '1 day') g(dte)
where g.dte < o.end_time;

您可以使用子查询获取每一天的跨度。

Answer 3

with t (startTime, endTime) as (values
('2017-09-09 6:56:32'::timestamptz,'2017-09-10 0:00:00'::timestamptz),
('2017-09-10 0:00:00','2017-09-11 0:00:00'),
('2017-09-11 0:00:00','2017-09-12 0:00:00'),
('2017-09-12 0:00:00','2017-09-13 0:00:00'),
('2017-09-13 0:00:00','2017-09-13 14:22:45'))
select startTime, endTime, upper(i) - lower(i) as a
from
    (
        select tstzrange(startTime, endTime) as tstzr, startTime, endTime
        from t
    ) t
    inner join (
        select tstzrange(d, d + interval '1 day') as d
        from 
        generate_series (
            (select min(startTime)::date from t),
            (select max(endTime) from t),
            '1 day'
        ) gs (d)
    ) gs on d && tstzr
    cross join lateral (
        select tstzr * d as i
    ) cjl
;
       starttime        |        endtime         |    a     
------------------------+------------------------+----------
 2017-09-09 06:56:32-03 | 2017-09-10 00:00:00-03 | 17:03:28
 2017-09-10 00:00:00-03 | 2017-09-11 00:00:00-03 | 1 day
 2017-09-11 00:00:00-03 | 2017-09-12 00:00:00-03 | 1 day
 2017-09-12 00:00:00-03 | 2017-09-13 00:00:00-03 | 1 day
 2017-09-13 00:00:00-03 | 2017-09-13 14:22:45-03 | 14:22:45

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