mysql 在不删除数据的时，同时重新更新主键id

1，删除原有主键：

ALTER TABLE `table_name` DROP `id`;

2，添加新主键字段：
ALTER TABLE `table_name` ADD `id` MEDIUMINT( 8 ) NOT NULL FIRST;

3，设置新主键：

ALTER TABLE `table_name` MODIFY COLUMN `id` MEDIUMINT( 8 ) NOT NULL AUTO_INCREMENT,ADD PRIMARY KEY(id);

 

4.导入数据 

 insert into `b` select * from `a`

例子：  

ALTER TABLE `a` DROP `id`;

alter table `a` AUTO_INCREMENT=1000000;

ALTER TABLE `a` ADD `id` MEDIUMINT( 8 ) NOT NULL FIRST;

ALTER TABLE `a` MODIFY COLUMN `id` MEDIUMINT( 8 ) NOT NULL AUTO_INCREMENT,ADD PRIMARY KEY(id);

insert into `b` select * from `a`