TSQL get unique (not overlapping) datetime ranges - tsql

Question

This is a question like this: TSQL get overlapping periods from datetime ranges but with a different result request.
This is the table:
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*/
I need the unique not overlapping datetime ranges table.
In the before example the result would be:
'2013-04-07 08:00','2013-04-07 13:00'
'2013-04-07 14:00','2013-04-07 17:00'
'2013-04-08 08:00','2013-04-08 20:00'
It is not very important if could be time fragmentation such as:
'2013-04-08 08:00','2013-04-08 13:00'
'2013-04-08 12:00','2013-04-08 20:00'
--EDIT--
Another example:
create table period (
id int,
starttime datetime,
endtime datetime,
type varchar(64)
);
insert into period values (1,'2013-06-13 8:30','2013-06-13 12:30','');
insert into period values (2,'2013-06-13 8:38','2013-06-13 12:38','');
insert into period values (3,'2013-06-13 13:18','2013-06-13 17:45','');
insert into period values (4,'2013-06-13 13:30','2013-06-13 17:30','');
insert into period values (5,'2013-06-13 20:00','2013-06-13 23:59','');
this should return:
2013-06-13 08:30 - 2013-06-13 12:38
2013-06-13 13:18 - 2013-06-13 17:45
2013-06-13 20:00 - 2013-06-13 23:59

Answer 1

But you have only one non-overlapping period, or did I understand the question wrong?
select *
from period t
where id in (
select t1.id
from period t1
join period t2 on t1.id <> t2.id
where t2.endtime <= t1.starttime or t2.starttime >= t1.endtime
group by t1.id
having count(*) + 1 = (select count(*) from period)
)
Result:
'2013-04-07 14:00','2013-04-07 17:00'
Update: Ok, so you want to merge overlapping ranges. Try this:
select starttime, endtime
from period
where id in (
select t1.id
from period t1
join period t2 on t1.id <> t2.id
where t2.endtime < t1.starttime or t2.starttime > t1.endtime
group by t1.id
having count(*) + 1 = (select count(*) from period)
)
union all
select min(start), max(fin) from (
select
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) overlaps
group by datepart(dd, start), datepart(dd, fin)

Answer 2

I found this solution... I think this is not the best way, but seems to work.
DECLARE #union_unique TABLE (id INT IDENTITY(1, 1) primary key ,starttime datetime,endtime datetime)
DECLARE #idset TABLE (id int)
DECLARE #i int
SET #i = 1
IF (SELECT COUNT(*) FROM period) > 0
WHILE (#i <= (SELECT MAX(id) FROM period))
BEGIN
delete from #idset
insert into #idset
select distinct t2.id
from period t1
join #union_unique t2 on convert(date, t1.starttime)=convert(date, t2.starttime)
where t1.id=#i and
(
t1.starttime >= t2.starttime and t1.starttime <= t2.endtime
or
t1.endtime >= t2.starttime and t1.endtime <= t2.endtime
or
t1.starttime <= t2.starttime and t1.endtime >= t2.endtime
)
if(select count(*) from #idset)=0
insert into #union_unique (starttime, endtime) select starttime, endtime from period where id=#i
else
BEGIN
insert into #union_unique (starttime, endtime)
select
min(starttime),
max(endtime)
from (
select starttime, endtime from #union_unique where id in (select id from #idset)
union
select starttime, endtime from period where id=#i
) alll
delete from #union_unique where id in (select id from #idset)
END
SET #i = #i + 1
END
select * from #union_unique order by starttime