mysql 在不刪除數據的時，同時重新更新主鍵id

1，刪除原有主鍵：

ALTER TABLE `table_name` DROP `id`;

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

3，設置新主鍵：

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

 

4.導入數據 

 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`