primary key†alter table テーブル名 add primary key(カラム); auto increment†alter table テーブル名 modify catid int auto_increment; 確認†describe テーブル名; +---------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+----------------+ | catid | int(11) | NO | PRI | NULL | auto_increment | | catname | varchar(10) | YES | | NULL | | +---------+-------------+------+-----+---------+----------------+ |