Calculate time correctly between 2 date range - sql

Question

I am working with the Datetime column where I am having trouble calculating the Time because of overlapping in time.
This is my sample data
Declare #T table (ID Int, InTime Datetime,OutTime Datetime)
Insert into #T values (1,'2020-08-23 09:26:07.000','2020-08-23 09:57:55.000')
Insert into #T values (1,'2020-08-23 14:09:08.000','2020-08-26 08:13:45.000')
Insert into #T values (1,'2020-08-24 11:14:37.000','2020-08-24 18:07:25.000')
Insert into #T values (1,'2020-08-25 09:19:38.000','2020-08-25 19:19:29.000')
Insert into #T values (1,'2020-08-26 08:13:50.000','2020-08-28 08:39:23.000')
Insert into #T values (1,'2020-08-27 08:42:16.000','2020-08-27 11:38:06.000')
Insert into #T values (1,'2020-08-27 09:51:14.000','2020-08-28 18:23:06.000')
Insert into #T values (1,'2020-08-29 09:51:14.000','2020-08-30 18:23:06.000')
My Expected Output:
+----+-------------------------+--------------------------+
| ID | InTime | OutTime |
+----+-------------------------+--------------------------+
| 1 | 2020-08-23 09:26:07.000 | 2020-08-23 09:57:55.000 |
| 1 | 2020-08-23 14:09:08.000 | 2020-08-26 08:13:45.000 |
| 1 | 2020-08-26 08:13:50.000 | 2020-08-28 08:39:23.000 |
| 1 | 2020-08-29 09:51:14.000 | 2020-08-30 18:23:06.000 |
+----+-------------------------+--------------------------+
If you see the 2nd entry in a table where my Intime is 2020-08-23 14:09:08.000 and outTime is 2020-08-26 08:13:45.000. So if there is any entry in a table between 23 and 26 we should skip that entry. so In out table we need to skip 24th and 25th entry.
Can someone please help me with this query. Any help will be appreciated
I tried this link but couldn't understand the logic Link

Answer 1

This is a classical case of "aggregating intervals". Snodgrass give a classical query to do that :
WITH
T0 AS
(SELECT PRE.id,
PRE.intime AS D1, PRE.outtime AS F1,
DER.intime AS D2, DER.outtime AS F2
FROM #T PRE
INNER JOIN #T DER
ON PRE.intime <= DER.outtime
AND PRE.id = DER.id)
SELECT DISTINCT id, D1 AS intime, F2 AS outtime
FROM T0 AS I
WHERE NOT EXISTS (SELECT *
FROM #T SI1
WHERE (SI1.intime < I.D1
AND I.D1 <= SI1.outtime
AND I.id = SI1.id )
OR (SI1.intime <= I.F2
AND I.F2 < SI1.outtime
AND I.id = SI1.id))
AND NOT EXISTS (SELECT *
FROM #T SI2
WHERE D1 < SI2.intime
AND SI2.intime <= F2
AND I.id = SI2.id
AND NOT EXISTS (SELECT *
FROM #T SI3
WHERE SI3.intime < SI2.intime
AND SI2.intime <= SI3.outtime
AND SI2.id = SI3.id ));
Chris Date give another version :
WITH T
AS (SELECT F.intime, L.outtime, F.id
FROM #T AS F
JOIN #T AS L
ON F.outtime <= L.outtime
AND F.id = L.id
INNER JOIN #T AS E
ON F.id = E.id
GROUP BY F.intime, L.outtime, F.id
HAVING COUNT(CASE
WHEN (E.intime < F.intime AND F.intime <= E.outtime)
OR (E.intime <= L.outtime AND L.outtime < E.outtime)
THEN 1
END) = 0)
SELECT id, intime, MIN(outtime) AS outtime
FROM T
GROUP BY id, intime;
And finally one I wrote :
WITH
T0 AS -- suprime les périodes incluses
(SELECT DISTINCT Tout.id, Tout.intime, Tout.outtime
FROM #T AS Tout
WHERE NOT EXISTS(SELECT *
FROM #T AS Tin
WHERE Tout.intime >= Tin.intime
AND Tout.outtime < Tin.outtime
AND Tout.id = Tin.id)),
T1 AS -- ancres : périodes de tête...
(SELECT Ta.*, 1 AS ITERATION
FROM T0 AS Ta
WHERE NOT EXISTS(SELECT *
FROM T0 AS Tb
WHERE Tb.outtime >= Ta.intime
AND Tb.outtime < Ta.outtime
AND Tb.id = Ta.id)
UNION ALL -- itération sur période dont le debut est inclus dans les bornes de la période ancre
SELECT T1.id, T1.intime, T0.outtime, T1.ITERATION + 1
FROM T1
INNER JOIN T0
ON T1.intime < T0.intime
AND T1.outtime >= T0.intime
AND T1.outtime < T0.outtime
AND T1.id = T0.id),
T2 AS
(SELECT *, ROW_NUMBER() OVER(PARTITION BY id, intime ORDER BY DATEDIFF(s, intime, outtime) DESC) AS N1,
ROW_NUMBER() OVER(PARTITION BY id, outtime ORDER BY DATEDIFF(s, intime, outtime) DESC) AS N2
FROM T1)
SELECT id, intime, outtime
FROM T2
WHERE N1 = 1 AND N2 = 1;
Which is a recursive Query
Itzik Ben Gan has done some more sophisticated and performant queries...