sql group by

create table Book
(
BookID int primary key identity(1,1),
BookNO nvarchar(50),
BookName nvarchar(50),
[Year] int,
Number int
)

insert into Book(BookNO,BookName,[Year],Number) values('NO001','指环王1',2012,1000);
insert into Book(BookNO,BookName,[Year],Number) values('NO001','指环王1',2014,2000);
insert into Book(BookNO,BookName,[Year],Number) values('NO002','指环王2',2013,1000);
insert into Book(BookNO,BookName,[Year],Number) values('NO002','指环王2',2014,2000);
insert into Book(BookNO,BookName,[Year],Number) values('NO003','指环王3',2015,2000);

select * from Book;

--此方法不能获取Number数据
select BookNO,BookName,max([Year])as [Year] from Book
group by BookNO,BookName

--此方法能显示Number数据
select * from Book b
where [Year]=(select max([Year]) from Book where BookNO=b.BookNO)
order by BookNO asc;