TSQL query to sum time periods per range [closed] - sql-server

Question

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Closed 10 years ago.
I need to create a query to sum day's hours and night's hours from a range intersec.
For example with this range:
8AM-8PM -> day
8PM-8AM -> night
and one or more start-end time period:
7.30AM 10.00PM
I would like to get this values:
12 day's hours
2.5 night's hours
I don't know which is the bast way to accomplish this function.

Answer 1

As i wrote in my comment, it is a brain teaser. I hope you can combine this with your code.
declare #t table(datefrom smalldatetime, dateto smalldatetime)
insert #t values('2012-01-01 10:30', '2012-01-02 09:00')
insert #t values('2012-01-01 08:00', '2012-01-02 20:20')
insert #t values('2012-01-01 19:00', '2012-01-02 13:00')
insert #t values('2012-01-01 20:00', '2012-01-02 00:00')
insert #t values('2012-01-01 23:00', '2012-01-03 00:00')
select datefrom, dateto, day, cast(datediff(minute, datefrom, dateto)/60.0 - day as decimal(9,2)) night
from #t t
cross apply
(select dateadd(day, datediff(hour, '1900-01-01 20:00', datefrom)/24, '1900-01-02 08:00') a,
dateadd(day, datediff(hour, '1901-01-01 09:00', dateto)/24, '1901-01-01 20:00' ) b) c
cross apply
(select cast(((datediff(hour, a, b) - 12 * datediff(day, a,b)) * 60
+case when a < datefrom then -datediff(minute, a, datefrom) else 0 end
+case when b > dateto then +datediff(minute, b, dateto) else 0 end) / 60.0 as decimal(9,2)) day) e
Result:
datefrom dateto day night
2012-01-01 10:30 2012-01-02 09:00:00 10.50 12.00
2012-01-01 08:00 2012-01-02 20:20:00 24.00 12.33
2012-01-01 19:00 2012-01-02 13:00:00 6.00 12.00
2012-01-01 20:00 2012-01-02 00:00:00 0.00 4.00
2012-01-01 23:00 2012-01-03 00:00:00 12.00 13.00

Answer 2

Sorry for adding another answer. But i realized that it seems you only handle time, my other solution operates on several days. Here is a solution that handle time only:
declare #t table(timefrom time(0), timeto time(0))
insert #t values('10:30', '21:30')
insert #t values('07:00', '20:20')
insert #t values('19:00', '21:00')
insert #t values('00:00', '23:59')
insert #t values('00:00', '00:00')
select timefrom, timeto,
cast(dayminutes/60.0 as decimal(5,2)) [day hours]
,cast((datediff(minute, timefrom, timeto) - a.dayminutes)/60.0 as decimal(5,2)) [night hours]
from #t
cross apply
(select datediff(minute, case when timefrom > '08:00' then timefrom else '08:00' end
,case when timeto < '20:00' then case when
timeto < '08:00' then '08:00' else timeto end else '20:00' end ) dayminutes) a
Result:
timefrom timeto day hours night hours
10:30:00 21:30:00 9.50 1.50
07:00:00 20:20:00 12.00 1.33
19:00:00 21:00:00 1.00 1.00
00:00:00 23:59:00 12.00 11.98
00:00:00 00:00:00 0.00 0.00