如何增加一个虚拟字段?

[mlxq1002]

CREATE TABLE `book` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `book_name` varchar(100) NOT NULL,
  `book_num` int(10) unsigned NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

select * from book;

结果:  id  book_name   book_num  [要增加一个虚拟字段 type ,值等于1]

如何在查询结果中， 增加一个虚拟字段 type=1 呢？

[WWWWA]

select *,1 as `type` from book;