MySQL 8.0

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create table gp(gpid int);
insert into gp(gpid) values
  (3), (5), (7);

Records: 3  Duplicates: 0  Warnings: 0

select * from gp;

gpid

3

5

7

UPDATE gp 
INNER JOIN (
  SELECT gpid, ROW_NUMBER() OVER (ORDER BY gpid) AS new_gpid
  FROM gp
) t ON t.gpid = gp.gpid
SET gp.gpid = t.new_gpid;

Rows matched: 3  Changed: 3  Warnings: 0

select * from gp;

gpid

1

2

3