CREATE TABLE demo(
 id INT,
 name varchar(20)
);

insert into demo(id, name)
values
(1, 'alfa'),
(1, 'beta'),
(1, 'gama'),
(1, 'delta'),
(1, 'teta');

select * from demo;

id  name
1   alfa
1   beta
1   gama
1   delta
1   teta

DECLARE @counter INT = 15;

UPDATE demo SET id = @counter, @counter = @counter + 1 WHERE id = 1;

select * from demo;

id  name
16  alfa
17  beta
18  gama
19  delta
20  teta