Oracle 18c

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CREATE TABLE table_name ( sno, id, start_date, end_date ) AS
SELECT 1, 1, DATE '2019-10-11', DATE '2019-10-11' FROM DUAL UNION ALL
SELECT 2, 1, DATE '2019-11-04', DATE '2019-12-11' FROM DUAL UNION ALL
SELECT 3, 1, DATE '2019-11-05', DATE '2019-11-10' FROM DUAL UNION ALL
SELECT 4, 1, DATE '2019-11-06', DATE '2019-11-10' FROM DUAL UNION ALL
SELECT 5, 1, DATE '2019-11-20', DATE '2019-12-20' FROM DUAL UNION ALL
SELECT 6, 1, DATE '2020-01-01', DATE '2020-01-20' FROM DUAL UNION ALL
SELECT 7, 1, DATE '2020-01-15', DATE '2020-03-25' FROM DUAL;
7 rows affected

ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
SELECT id, start_date, end_date
FROM   table_name
MATCH_RECOGNIZE (
  PARTITION BY id
  ORDER     BY start_date
  MEASURES  FIRST(start_date) AS start_date,
            MAX(end_date) AS end_date
  PATTERN   ( overlapping_dates* last_date )
  DEFINE    overlapping_dates as MAX(end_date) >= NEXT(start_date)  
);


ID
START_DATE
END_DATE


1
2019-10-11 00:00:00
2019-10-11 00:00:00

1
2019-11-04 00:00:00
2019-12-20 00:00:00

1
2020-01-01 00:00:00
2020-03-25 00:00:00

ID	START_DATE	END_DATE
1	2019-10-11 00:00:00	2019-10-11 00:00:00
1	2019-11-04 00:00:00	2019-12-20 00:00:00
1	2020-01-01 00:00:00	2020-03-25 00:00:00