MySQL 8.0

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select version();


version()


8.0.36


CREATE TABLE availibility ( 
   id int NOT NULL,
   start_date date NOT NULL, 
   end_date date DEFAULT NULL, 
   status tinyint NOT NULL DEFAULT '1'
) ENGINE=InnoDB;

INSERT INTO availibility (id, start_date, end_date, status) VALUES (1,'2024-02-01', '2024-02-10', 1), (2,'2024-02-21','2024-02-29',1);

Records: 2  Duplicates: 0  Warnings: 0


SELECT 
  id,
  start_date,
  end_date,
  status
FROM availibility

UNION ALL

SELECT 
  NULL, 
  DATE_ADD(a1.end_date,INTERVAL 1 DAY),
  DATE_ADD(a2.start_date, INTERVAL -1 DAY),
  0
FROM availibility a1 
INNER JOIN availibility a2 ON a2.id=2
WHERE a1.id=1
ORDER BY start_date


id
start_date
end_date
status


1
2024-02-01
2024-02-10
1

null
2024-02-11
2024-02-20
0

2
2024-02-21
2024-02-29
1


(SELECT * FROM availibility order by start_date) 
  UNION ALL 
( WITH ranked_end_date AS ( SELECT *,LEAD(start_date) OVER (ORDER BY start_date) AS next_start_date 
                            FROM availibility ) 
SELECT NULL AS id, end_date + INTERVAL 1 DAY , next_start_date - INTERVAL 1 DAY, 0 AS status 
FROM ranked_end_date 
WHERE next_start_date is not null AND DATEDIFF(next_start_date, end_date) > 1 ) 
ORDER BY start_date


id
start_date
end_date
status


1
2024-02-01
2024-02-10
1

null
2024-02-11
2024-02-20
0

2
2024-02-21
2024-02-29
1

id	start_date	end_date	status
1	2024-02-01	2024-02-10	1
null	2024-02-11	2024-02-20	0
2	2024-02-21	2024-02-29	1