MariaDB 10.3

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

CREATE TABLE contact (
    Id int primary key auto_increment, 
    ContactNumber int 
  );
INSERT INTO contact (ContactNumber)
VALUES (1), (5), (100), (3) ;

Records: 4  Duplicates: 0  Warnings: 0


select * from contact ;


Id
ContactNumber


1
1

2
5

3
100

4
3


    UPDATE
        contact AS m
      JOIN
        ( SELECT Id, row_number() OVER (ORDER BY Id) AS rn 
           FROM contact
        ) AS sub
      ON  m.Id = sub.Id
    SET
        m.ContactNumber = sub.rn + 500
     ;

Rows matched: 4  Changed: 4  Warnings: 0


select * from contact ;


Id
ContactNumber


1
501

2
502

3
503

4
504