Oracle 18c

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CREATE TABLE table_name ( dt, Emp_ID, Dummy ) AS
SELECT DATE '2021-01-01', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-02', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-03', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-04', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-05', 5, 0 FROM DUAL UNION ALL
SELECT DATE '2021-01-06', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-07', 5, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-01', 8, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-02', 8, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-03', 8, 1 FROM DUAL UNION ALL
SELECT DATE '2021-01-04', 8, 0 FROM DUAL UNION ALL
SELECT DATE '2021-01-05', 8, 0 FROM DUAL UNION ALL
SELECT DATE '2021-01-06', 8, 0 FROM DUAL UNION ALL
SELECT DATE '2021-01-07', 8, 1 FROM DUAL;
14 rows affected

ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
SELECT *
FROM   table_name
MATCH_RECOGNIZE (
  PARTITION BY Emp_ID
  ORDER     BY dt
  MEASURES
    FIRST(dt) AS min_date,
    LAST(dt)  AS max_date,
    MATCH_NUMBER() AS group_number
  PATTERN (one+)
  DEFINE
    one AS dummy = 1
)


EMP_ID
MIN_DATE
MAX_DATE
GROUP_NUMBER


5
2021-01-01 00:00:00
2021-01-04 00:00:00
1

5
2021-01-06 00:00:00
2021-01-07 00:00:00
2

8
2021-01-01 00:00:00
2021-01-03 00:00:00
1

8
2021-01-07 00:00:00
2021-01-07 00:00:00
2

EMP_ID	MIN_DATE	MAX_DATE	GROUP_NUMBER
5	2021-01-01 00:00:00	2021-01-04 00:00:00	1
5	2021-01-06 00:00:00	2021-01-07 00:00:00	2
8	2021-01-01 00:00:00	2021-01-03 00:00:00	1
8	2021-01-07 00:00:00	2021-01-07 00:00:00	2