SQL Server 2019

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CREATE TABLE tablename (
  id_conf INTEGER,
  position INTEGER,
  proj_id INTEGER,
  colspan_no INTEGER,
  colspan_title VARCHAR(10)
);

INSERT INTO tablename (id_conf, position, proj_id, colspan_no, colspan_title) VALUES
  ('4460', '1', '575', '1', 'prod1'),
  ('4461', '2', '575', '5', 'prod2'),
  ('4462', '3', '575', '0', null),
  ('4463', '4', '575', '0', null),
  ('4464', '5', '575', '0', null),
  ('4465', '6', '575', '0', null),
  ('4466', '7', '575', '2', 'prod3'),
  ('4467', '8', '575', '0', null),
  ('4468', '9', '575', '3', 'prod4'),
  ('4469', '11', '575', '0', null),
  ('4470', '10', '575', '0', null),
  ('4471', '12', '575', '3', 'prod5'),
  ('4472', '14', '575', '0', null),
  ('4473', '13', '575', '0', null),
  ('4474', '15', '575', '3', 'prod6'),
  ('4475', '17', '575', '0', null),
  ('4476', '16', '575', '0', null);
17 rows affected

WITH cte AS (
  SELECT *, FIRST_VALUE(colspan_title) OVER (PARTITION BY grp ORDER BY id_conf) title
  FROM (
    SELECT *, SUM(colspan_no) OVER (ORDER BY id_conf) grp
    FROM tablename
  ) t  
)
UPDATE cte 
SET colspan_title = title
WHERE colspan_no = 0
11 rows affected

SELECT * FROM tablename


id_conf
position
proj_id
colspan_no
colspan_title


4460
1
575
1
prod1

4461
2
575
5
prod2

4462
3
575
0
prod2

4463
4
575
0
prod2

4464
5
575
0
prod2

4465
6
575
0
prod2

4466
7
575
2
prod3

4467
8
575
0
prod3

4468
9
575
3
prod4

4469
11
575
0
prod4

4470
10
575
0
prod4

4471
12
575
3
prod5

4472
14
575
0
prod5

4473
13
575
0
prod5

4474
15
575
3
prod6

4475
17
575
0
prod6

4476
16
575
0
prod6

id_conf	position	proj_id	colspan_no	colspan_title
4460	1	575	1	prod1
4461	2	575	5	prod2
4462	3	575	0	prod2
4463	4	575	0	prod2
4464	5	575	0	prod2
4465	6	575	0	prod2
4466	7	575	2	prod3
4467	8	575	0	prod3
4468	9	575	3	prod4
4469	11	575	0	prod4
4470	10	575	0	prod4
4471	12	575	3	prod5
4472	14	575	0	prod5
4473	13	575	0	prod5
4474	15	575	3	prod6
4475	17	575	0	prod6
4476	16	575	0	prod6