MySQL 8.0

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create table progetti (
  id	int,
  start_date	date,
  end_date      date
);

insert into progetti values
(1,	'2022-01-01',	'2023-06-30'),
(2,	'2022-01-01',	'2022-12-31');

Records: 2  Duplicates: 0  Warnings: 0


create table s (
  period	varchar(20),
  total int
);

insert into s values
('03-2022',	2),
('04-2022',	1),
('05-2022',	3),
('06-2022',	2);

Records: 4  Duplicates: 0  Warnings: 0


WITH RECURSIVE dates AS 
(
    SELECT start_date as period, end_date
    FROM progetti
    WHERE id = 1
    UNION ALL
    SELECT DATE_ADD(period, INTERVAL 1 MONTH), end_date
    FROM dates 
    WHERE DATE_ADD(period, INTERVAL 1 MONTH) < end_date
)
SELECT DATE_FORMAT(d.period, '%m-%Y') AS period, COALESCE(total, 0) AS total
FROM dates d
LEFT JOIN s on s.period = DATE_FORMAT(d.period, '%m-%Y')


period
total


01-2022
0

02-2022
0

03-2022
2

04-2022
1

05-2022
3

06-2022
2

07-2022
0

08-2022
0

09-2022
0

10-2022
0

11-2022
0

12-2022
0

01-2023
0

02-2023
0

03-2023
0

04-2023
0

05-2023
0

06-2023
0

period	total
01-2022	0
02-2022	0
03-2022	2
04-2022	1
05-2022	3
06-2022	2
07-2022	0
08-2022	0
09-2022	0
10-2022	0
11-2022	0
12-2022	0
01-2023	0
02-2023	0
03-2023	0
04-2023	0
05-2023	0
06-2023	0