create database db;
use db;
CREATE TABLE `sb` (
  `id` int(11) NOT NULL auto_increment ,
  `k` int(10) unsigned NOT NULL DEFAULT '0',
  `c` char(120) NOT NULL DEFAULT '',
  `pad` char(60) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  KEY `k_1` (`k`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci MAX_ROWS=1000000;

let $loop = 129;
while ($loop) {
 insert into sb(id, k, c, pad) values(NULL, 1, 'test', 'test');
 dec $loop;
}
alter table sb modify  id int not null;
alter table sb drop primary key, add column c1 int not null auto_increment, add key(c1);