I am using workbench/j Postgres DB for my query which is as follows -
Input
ID |utc_tune_start_time |utc_tune_end_time
----------------------------------------------
A |04-03-2019 19:00:00 |04-03-2019 20:00:00
----------------------------------------------
A |04-03-2019 23:00:00 |05-03-2019 01:00:00
-----------------------------------------------
A |05-03-2019 10:00:00 |05-03-2019 10:30:00
-----------------------------------------------
Output
ID |Day |Duration in Minutes
----------------------------------------
A |04-03-2019 |120
-----------------------------------
A |05-03-2019 |90
-----------------------------------
I require the duration elapsed from the utc_tune_start_time till the end of the day and similarly, the time elapsed for utc_tune_end_time since the start of the day.
Thanks for your clarifications. This is possible with some case statements. Basically, if utc_tune_start_time and utc_tune_end_time are on the same day, just use the difference, otherwise calculate the difference from the end or start of the day.
WITH all_activity as (
select date_trunc('day', utc_tune_start_time) as day,
case when date_trunc('day', utc_tune_start_time) =
date_trunc('day', utc_tune_end_time)
then utc_tune_end_time - utc_tune_start_time
else date_trunc('day', utc_tune_start_time) +
interval '1 day' - utc_tune_start_time
end as time_spent
from test
UNION ALL
select date_trunc('day', utc_tune_end_time),
case when date_trunc('day', utc_tune_start_time) =
date_trunc('day', utc_tune_end_time)
then null -- we already calculated this earlier
else utc_tune_end_time - date_trunc('day', utc_tune_end_time)
end
FROM test
)
select day, sum(time_spent)
FROM all_activity
GROUP BY day;
day | sum
---------------------+----------
2019-03-04 00:00:00 | 02:00:00
2019-03-05 00:00:00 | 01:30:00
(2 rows)
Related
I have the time and the values in the data base. I need to calculate for a given month the average during each hour i.e.
YYYY-mm-dd (the day can be omitted)
2021-01-01 00:00:00 value=avg(values from 00:00:00 until 00:59:59 for every day of this month at this hour interval)
2021-01-01 01:00:00 value=avg(values from 01:00:00 until 01:59:59 idem as above)
...
2021-01-01 23:00:00 value=avg(values from 23:00:00 until 23:59:59)
2021-02-01 00:00:00 value=avg(values from 00:00:00 until 00:59:59)
2021-02-01 01:00:00 value=avg(values from 01:00:00 until 01:59:59)
...
2021-02-01 23:00:00 value=avg(values from 23:00:00 until 23:59:59)
...
You can use date_trunc('hour', datestamp) in a GROUP BY statement, something like this.
SELECT DATE_TRUNC('hour', datestamp) hour_beginning, AVG(value) average_value
FROM mytable
WHERE datestamp >= '2021-01-01'
AND datestamp < '2021-02-01'
GROUP BY DATE_TRUNC('hour', datestamp)
ORDER BY DATE_TRUNC('hour', datestamp)
To generalize, in place of DATE_TRUNC you can use any injective function.
You could use
to_char(datestamp, 'YYYY-MM-01 HH24:00:00')
to get one result row per hour for every month in your date range.
SELECT to_char(datestamp, 'YYYY-MM-01 HH24:00:00') hour,
AVG(value) average_value
FROM mytable
GROUP BY to_char(datestamp, 'YYYY-MM-01 HH24:00:00')
ORDER BY to_char(datestamp, 'YYYY-MM-01 HH24:00:00')
I also have the question how do i get code block to work on stack overflow but that's a side issue.
I have this quasi-code that works:
select
*
from
unnest('{2018-6-1,2018-7-1,2018-8-1,2018-9-1}'::date[],
'{2018-6-30,2018-7-31,2018-8-31,2018-9-30}'::date[]
) zdate(start_date, end_date)
left join lateral pipe_f(zdate...
But now I want it to work from 6/1/2018 until now(). What's the best way to do this.
Oh, postgresql 10. yay!!
Your query gives a list of first and last days of months between "2018-06-01" and now. So I am assuming that you want to this in a more dynamic way:
demo: db<>fiddle
SELECT
start_date,
(start_date + interval '1 month -1 day')::date as end_date
FROM (
SELECT generate_series('2018-6-1', now(), interval '1 month')::date as start_date
)s
Result:
start_date end_date
2018-06-01 2018-06-30
2018-07-01 2018-07-31
2018-08-01 2018-08-31
2018-09-01 2018-09-30
2018-10-01 2018-10-31
generate_series(timestamp, timestamp, interval) generates a list of timestamps. Starting with "2018-06-01" until now() with the 1 month interval gives this:
start_date
2018-06-01 00:00:00+01
2018-07-01 00:00:00+01
2018-08-01 00:00:00+01
2018-09-01 00:00:00+01
2018-10-01 00:00:00+01
These timestamps are converted into dates with ::date cast.
Then I add 1 month to get the next month. But as we are interested in the last day of the previous month I subtract one day again (+ interval '1 month -1 day')
Another option that's more ANSI-compliant is to use a recursive CTE:
WITH RECURSIVE
dates(d) AS
(
SELECT '2018-06-01'::TIMESTAMP
UNION ALL
SELECT d + INTERVAL '1 month'
FROM dates
WHERE d + INTERVAL '1 month' <= '2018-10-01'
)
SELECT
d AS start_date,
-- add 1 month, then subtract 1 day, to get end of current month
(d + interval '1 month') - interval '1 day' AS end_date
FROM dates
Have two dates - '2018-05-01' and '2018-06-01'. I would like to expand this window to the past by day difference of those dates.
SELECT * FROM data
WHERE
start_time > CAST('2018-05-01' AS timestamptz) - INTERVAL '30 DAY'
AND start_time < CAST('2018-06-01' AS timestamptz)
How can I replace INTERVAL '30 DAY' with number of days between given dates without explicitly defining number of days? I know to calculate day difference:
date_part('day',age('2018-05-01', '2018-06-01'))
But not sure how to incorporate into the substraction. Dates and days between them will change.
You can use date_trunc('mon', some_date_expression) to round down to the start of a month:
select date_trunc('mon', now() - '3 mon'::interval) as date_begin
, date_trunc('mon', now() - '1 day'::interval) as date_end
;
Result
date_begin | date_end
------------------------+------------------------
2018-03-01 00:00:00+01 | 2018-06-01 00:00:00+02
(1 row)
You can simply subtract the difference from the start date:
with t (start_date, end_date) as (
values (date '2018-05-01', date '2018-06-01')
)
select start_date - (end_date - start_date) as new_start,
end_date
from t;
returns
new_start | new_end
-----------+-----------
2018-03-31 | 2018-06-01
Let's suppose I have a start date 2016-06-19 09:30:00 and an end date 2016-06-19 10:20:00
I would like to get the time that elapsed every hour before starting the next hour or before getting to the final time in seconds grouped by hour and date, the result I'm trying to achieve (without having any success) would be something like this:
hour | date | time_elapsed_in_seconds
9 | 2016-06-19 | 1800 (there are 1800 seconds between 09:30:00 and 10:00:00)
10 | 2016-06-19 | 1200 (there are 1200 seconds between 10:00:00 and 10:20:00)
Try this :
with table1 as (
select '2016-06-19 09:30:00'::timestamp without time zone start_date,'2016-06-19 10:20:00'::timestamp without time zone end_date
)
select extract(hour from the_hour) "hour",the_hour::date "date",extract (epoch from (new_end-new_start)) "time_elapsed" from (
select the_hour,CASE WHEN date_trunc('hour',start_date)=the_hour then start_date else the_hour end new_start,
CASE WHEN date_trunc('hour',end_date)=the_hour then end_date else the_hour+'1 hour'::interval end new_end
from (
select generate_series(date_trunc('hour',start_date),end_date,'1 hour'::interval) the_hour,start_date,end_date from table1
) a
) b
I'm trying to come up with a query that will properly count that there are 25 hours on daylight savings. My table has a column of type timestampz called hourly_timestamp. The incorrect answer I have so far looks like this:
select EXTRACT(epoch FROM tomorrow-today)/3600
from(
select date_trunc('day', timezone('America/New_York', hourly_timestamp) as today ,
date_trunc('day', timezone('America/New_York', hourly_timestamp)))
+ '1 day'::interval as tomorrow
)t;
When this query executed during daylight savings time, I still only get 24 hours back and not 25. Any ideas how to do this correctly?
The number of hours varies with the clock.
with hours as (
select (timestamp with time zone '2014-11-01 00:00:00 America/New_York' + (n || ' hour')::interval) as hourly_timestamp
from generate_series(0, 72) n
)
select hourly_timestamp
, hourly_timestamp + interval '1' day as one_day_later
, hourly_timestamp + interval '1' day - hourly_timestamp as elapsed_time
from hours;
hourly_timestamp one_day_later elapsed_time
--
[snip]
2014-11-01 22:00:00-04 2014-11-02 22:00:00-05 1 day 01:00:00
2014-11-01 23:00:00-04 2014-11-02 23:00:00-05 1 day 01:00:00
2014-11-02 00:00:00-04 2014-11-03 00:00:00-05 1 day 01:00:00
2014-11-02 01:00:00-04 2014-11-03 01:00:00-05 1 day 01:00:00
2014-11-02 01:00:00-05 2014-11-03 01:00:00-05 1 day
2014-11-02 02:00:00-05 2014-11-03 02:00:00-05 1 day
2014-11-02 03:00:00-05 2014-11-03 03:00:00-05 1 day
2014-11-02 04:00:00-05 2014-11-03 04:00:00-05 1 day
[snip]
Note that 01:00 repeats, but with a different offset. Daylight savings time ends at 02:00, the clocks fall back and repeat the hour between 01:00 and 02:00, but since daylight savings time has ended, there are now five hours between the UTC and America/New_York time zones.
This similar query displays dates, not timestamps.
with dates as (
select (timestamp with time zone '2014-11-01 00:00:00 America/New_York' + (n || ' day')::interval) as daily_timestamp
from generate_series(0, 2) n
)
select daily_timestamp::date
, (daily_timestamp + interval '1' day)::date as one_day_later
, daily_timestamp + interval '1' day - daily_timestamp as elapsed_time
from dates;
daily_timestamp one_day_later elapsed_time
--
2014-11-01 2014-11-02 1 day
2014-11-02 2014-11-03 1 day 01:00:00
2014-11-03 2014-11-04 1 day
Where did you go wrong? By calculating the elapsed time after you truncated the time information. (Dates don't have time zones associated with them.) If I take the second query and cast "daily_timestamp" to a date in the common table expression, I get 24 hours, too.
with dates as (
select (timestamp with time zone '2014-11-01 00:00:00 America/New_York' + (n || ' day')::interval)::date as daily_timestamp
from generate_series(0, 2) n
)
select daily_timestamp::date
, (daily_timestamp + interval '1' day)::date as one_day_later
, daily_timestamp + interval '1' day - daily_timestamp as elapsed_time
from dates;
daily_timestamp one_day_later elapsed_time
--
2014-11-01 2014-11-02 1 day
2014-11-02 2014-11-03 1 day
2014-11-03 2014-11-04 1 day
You first have to do the extraction to epoch and then the calculations:
WITH test AS (
SELECT '2014-10-26'::timestamptz at time zone 'America/New_York' AS today,
'2014-10-27'::timestamptz at time zone 'America/New_York' AS tomorrow
)
SELECT
extract(epoch from tomorrow) - extract(epoch from today) AS seconds, -- 90000
(extract(epoch from tomorrow) - extract(epoch from today)) / 3600 AS hours -- 25
FROM test;