Oracle 18c

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CREATE TABLE empdepthist (
  loginName VARCHAR2(2),
  emp_name  VARCHAR2(6),
  dept_id   NUMBER,
  dept_name VARCHAR2(50),
  startDate DATE,
  endDate   DATE
);
ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MM-RR';
INSERT INTO empdepthist (loginName, emp_name, dept_id, dept_name, startDate, endDate )
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '18-09-17', '19-09-17' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '19-09-17', '28-09-17' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '28-09-17', '09-11-17' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5647, 'POLO Business',              '09-11-17', '15-03-19' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5647, 'POLO Business',              '15-03-19', '16-04-19' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5649, 'POLO Buss-Fixed Sales Mkt',  '16-04-19', '03-05-19' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5649, 'POLO Buss-Fixed Sales Mkt',  '03-05-19', '11-10-19' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5649, 'POLO Buss-Fixed Sales Mkt',  '11-10-19', '22-07-20' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5649, 'POLO Buss-Fixed Sales Mkt',  '22-07-20', '26-08-20' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '26-08-20', '17-02-21' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '17-02-21', '19-02-21' FROM DUAL UNION ALL
SELECT 'KK', 'KKLeo', 5652, 'POLO Business – Tech',       '19-02-21', null FROM DUAL
12 rows affected

SELECT *
FROM   empdepthist
MATCH_RECOGNIZE (
  PARTITION BY loginname
  ORDER BY startdate
  MEASURES
    FIRST(emp_name) AS emp_name,
    FIRST(dept_id) AS dept_id,
    FIRST(dept_name) AS dept_name,
    FIRST(startDate) AS startdate,
    FIRST(endDate) AS enddate
  ONE ROW PER MATCH
  PATTERN (same_dept+ $)
  DEFINE same_dept AS FIRST(dept_id) = dept_id
)


LOGINNAME
EMP_NAME
DEPT_ID
DEPT_NAME
STARTDATE
ENDDATE


KK
KKLeo
5652
POLO Business – Tech
26-08-20
17-02-21