TSQL get overlapping periods from datetime ranges - tsql

Question

I have a table with date range an i need the sum of overlapping periods (in hours) between its rows.
This is a schema example:
create table period (
id int,
starttime datetime,
endtime datetime,
type varchar(64)
);
insert into period values (1,'2013-04-07 8:00','2013-04-07 13:00','Work');
insert into period values (2,'2013-04-07 14:00','2013-04-07 17:00','Work');
insert into period values (3,'2013-04-08 8:00','2013-04-08 13:00','Work');
insert into period values (4,'2013-04-08 14:00','2013-04-08 17:00','Work');
insert into period values (5,'2013-04-07 10:00','2013-04-07 11:00','Holyday'); /* 1h overlapping with 1*/
insert into period values (6,'2013-04-08 10:00','2013-04-08 20:00','Transfer'); /* 6h overlapping with 3 and 4*/
insert into period values (7,'2013-04-08 11:00','2013-04-08 12:00','Test'); /* 1h overlapping with 3 and 6*/
And its fiddle: http://sqlfiddle.com/#!6/9ca31/10
I expect a sum of 8h overlapping hours:
1h (id 5 over id 1)
6h (id 6 over id 3 and 4)
1h (id 7 over id 3 and 6)
I check this: select overlapping datetime events with SQL but seems to not do what I need.
Thank you.

Answer 1

select sum(datediff(hh, case when t2.starttime > t1.starttime then t2.starttime else t1.starttime end,
case when t2.endtime > t1.endtime then t1.endtime else t2.endtime end))
from period t1
join period t2 on t1.id < t2.id
where t2.endtime > t1.starttime and t2.starttime < t1.endtime;
Updated to handle several overlaps:
select sum(datediff(hh, start, fin))
from (select distinct
case when t2.starttime > t1.starttime then t2.starttime else t1.starttime end as start,
case when t2.endtime > t1.endtime then t1.endtime else t2.endtime end as fin
from period t1
join period t2 on t1.id < t2.id
where t2.endtime > t1.starttime and t2.starttime < t1.endtime
) as overlaps;

Answer 2

I have some "dirty" solution. Hope this helps :)
with src as (
select
convert(varchar, starttime, 112) [start_date]
, cast(left(convert(varchar, starttime, 108), 2) as int) [start_time]
, convert(varchar, endtime, 112) [end_date]
, cast(left(convert(varchar, endtime, 108), 2) as int) [end_time]
, id
from [period]),
[gr] as (
select
row_number() over(order by s1.[start_date], s1.[start_time], s1.[end_time], s2.[start_time], s2.[end_time]) [no]
, s1.[start_date] [date]
, s1.[start_time] [t1]
, s1.[end_time] [t2]
, s2.[start_time] [t3]
, s2.[end_time] [t4]
from src s1
join src s2 on s1.[start_date] = s2.[start_date]
and s1.[end_date] = s2.[end_date]
and (s1.[start_time] between s2.[start_time] and s2.[end_time] or s1.[end_time] between s2.[start_time] and s2.[end_time])
and s1.id != s2.id),
[raw] as (
select [no], [date], [t1] [h] from [gr] union all
select [no], [date], [t2] from [gr] union all
select [no], [date], [t3] from [gr] union all
select [no], [date], [t4] from [gr]),
[max_min] as (
select [no], [date], max(h) [max_h], min(h) [min_h]
from [raw]
group by [no], [date]
),
[result] as (
select [raw].*
from [raw]
left join [max_min] on [raw].[no] = [max_min].[no]
and ([raw].h = [max_min].[max_h] or [raw].h = [max_min].[min_h])
where [max_min].[no] is null),
[final] as (
select distinct r1.[date], r1.h [start_h], r2.h [end_h], abs(r1.h - r2.h) [dif]
from [result] r1
join [result] r2 on r1.[no] = r2.[no]
where abs(r1.h - r2.h) > 0
and r1.h > r2.h)
select sum(dif) [overlapping hours] from [final]
SQLFiddle