Oracle 11g Release 2

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CREATE TABLE VEHICLE_GEARS ( vehicle_id, startdate, enddate, gear_id ) AS
SELECT '000000000', DATE '2014-02-25', DATE '2999-12-31', 302 FROM DUAL UNION ALL -- No duplicate vehicle & gear
SELECT '000000000', DATE '2006-12-15', DATE '2999-12-31', 604 FROM DUAL UNION ALL -- No duplicate vehicle & gear
SELECT '000000000', DATE '2006-12-15', DATE '2999-12-31', 605 FROM DUAL UNION ALL -- No duplicate vehicle & gear
SELECT '000000006', DATE '1991-07-01', DATE '2999-12-31', 601 FROM DUAL UNION ALL -- No duplicate vehicle & gear
SELECT '000000006', DATE '2016-01-18', DATE '2999-12-31', 605 FROM DUAL UNION ALL -- No duplicate vehicle & gear
SELECT '000000006', DATE '2012-02-20', DATE '2999-12-31', 804 FROM DUAL UNION ALL -- Overlaps previous
SELECT '000000006', DATE '1991-07-01', DATE '2999-12-31', 804 FROM DUAL UNION ALL -- Overlaps next
SELECT '000000147', DATE '1991-07-01', DATE '1992-10-08', 601 FROM DUAL UNION ALL -- Same end date as next start date
SELECT '000000147', DATE '1992-10-08', DATE '2999-12-31', 601 FROM DUAL UNION ALL -- Same start date as previous end date
SELECT '000000567', DATE '2018-01-01', DATE '2018-12-31', 203 FROM DUAL UNION ALL -- Overlaps next
SELECT '000000567', DATE '2018-12-01', DATE '2019-01-10', 203 FROM DUAL UNION ALL -- Overlaps previous and next
SELECT '000000567', DATE '2018-12-31', DATE '2019-01-10', 203 FROM DUAL UNION ALL -- Overlaps previous and next
SELECT '000000567', DATE '2018-12-31', DATE '2019-01-31', 203 FROM DUAL UNION ALL -- Overlaps previous
SELECT '000000567', DATE '2019-01-31', DATE '2019-02-28', 203 FROM DUAL           -- Same start date as previous

14 rows affected

VEHICLE_ID	STARTDATE	ENDDATE	GEAR_ID
000000006	20-FEB-12	31-DEC-99	804
000000567	31-DEC-18	31-JAN-19	203