从表中显示每个出版商的最新出版书籍的查询

Question

I'm trying to write a query that show latest published books from each publisher from a table like this

bookcode	Name	Publisher	PublishYr
61523	c++	Pearson	2018
54681	python	sybex	2017
45168	sql	RELX	2019
79137	c#	Macmillan	2016
89451	ccna	Pearson	2020
45187	lpic 1	RELX	2021
16497	ccnp	sybex	2018
19437	lpic 2	Penguin	2019

and desired table in query should be:

Publisher	name
Pearson	ccna
sybex	ccnp
RELX	lpic 1
Macmillan	c#
Penguin	lpic 2

Answer 1

Here is one way using window functions:

select * from (
   select * , row_number() over (partition by publisher order by PublishYr desc) rn
   from tablename
) t where rn = 1 

Answer 2

The query doesn't need a subquery if you use SELECT TOP(1) WITH TIES .

select top(1) with ties publisher, book_name, 
                   row_number() over (partition by Publisher 
                                      order by PublishYr desc) rn
from TableWithData
order by rn;

Answer 3

Get maximum year per publisher as subquery and join with source table.

Select tablename.Publisher, tablename.Name
From tablename
Inner Join (
    Select max(PublishYr) As MaxPublishYr, Publisher
    From tablename 
    Group By Publisher
) as Subqry on Subqry.Publisher = tablename.Publisher
    and Subqry.MaxPublishYr = tablename.PublishYr