If there is no primary key or unique key InnoDB will use an internally generated unique integer key and will physically store records in roughly insert order, as MyISAM does.
如果没有主键或唯一密钥，InnoDB将使用内部生成的唯一整数密钥，并将以粗略的插入顺序物理存储记录，如 MyISAM做到了。