SQL merge overlapping time intervals - sql

Question

I have a sqlite dataset like this
Startdate | Enddate | ID
2019-04-29 | 2019-05-04 | 12
2019-04-23 | 2019-04-25 | 533
2019-04-23 | 2019-04-24 | 44
2019-04-24 | 2019-04-25 | 79
I'm trying to get an output that is sorted in range from startdate to startdate plus day in a loop until last Endate.
The plan is to get all observation from min(Startdate) to min(Startdate) +1 and min(Startdate) plus +2 and so one
Range | ID
2019-04-23 2019-04-24 | 44
2019-04-23 2019-04-25 | 44
2019-04-23 2019-04-25 | 533
2019-04-23 2019-04-25 | 79
2019-04-23 2019-05-04 | 44
2019-04-23 2019-05-04 | 533
2019-04-23 2019-05-04 | 79
2019-04-23 2019-05-04 | 12
I'm not sure have to achieve this

Answer 1

I believe that the following will provide the results that you want :-
WITH cte(sdate,edate) AS
(
SELECT (SELECT min(startdate) FROM mytable),(SELECT min(startdate) FROM mytable)
UNION ALL
SELECT sdate,date(edate,'+1 days')
FROM cte
WHERE edate <= (
SELECT max(enddate) FROM mytable
)
LIMIT 1000 /* just in case limit to 1000 rows */
)
SELECT sdate||' '||edate AS Range, id
FROM cte
JOIN mytable ON startdate >= sdate
AND enddate <= edate
AND edate IN (SELECT enddate FROM mytable)
Example/Test/Demo
DROP TABLE IF EXISTS mytable;
CREATE TABLE IF NOT EXISTS mytable (startdate TEXT, enddate TEXT, id INTEGER PRIMARY KEY);
INSERT INTO mytable VALUES
('2019-04-29','2019-05-04',12),
('2019-04-23','2019-04-25',533),
('2019-04-23','2019-04-24',44),
('2019-04-24','2019-04-25',79)
;
WITH cte(sdate,edate) AS
(
SELECT (SELECT min(startdate) FROM mytable),(SELECT min(startdate) FROM mytable)
UNION ALL
SELECT sdate,date(edate,'+1 days')
FROM cte
WHERE edate <= (
SELECT max(enddate) FROM mytable
)
LIMIT 1000 /* just in case limit to 1000 rows */
)
SELECT sdate||' '||edate AS Range, id
FROM cte
JOIN mytable ON startdate >= sdate
AND enddate <= edate
AND edate IN (SELECT enddate FROM mytable)
;
DROP TABLE IF EXISTS mytable;
The result is :-
The only difference being the order of the ID column (I can't see any order from your expected result)
As per the comment LIMIT 1000 is not required