按最新出版的书返回作者+没有出版的书返回作者

Question

I have two tables :

•Table 1: Books
•Table 2: Authors

I have the following query:(This query returns all authors with book title and date published)

SELECT Authors.AuthorName, Books.BookTitle, Books.DatePublished, Books.Author
FROM Authors LEFT OUTER JOIN Books ON Authors.AuthorID = Books.Author

Problem:!!

I would like to return all Authors(Both who have books published . and those that dont have books published.

Condition (The authors that do have books. return only the latest published book)

I am able to get latest published book with the below query:

SELECT a.*    
FROM [Books] a left outer join Books b on a.Author = b.author and 
a.DatePublished < b.DatePublished where b.ISDN  is null

Question: How can i incorporate both these queries to return ALL the authors + authors with latest published book ?

Answer 1

Please try:

SELECT DISTINCT
    AuthorName, 
    BookTitle, 
    DatePublished, 
    Author 
FROM(
    SELECT 
        Authors.AuthorName, 
        Books.BookTitle, 
        Books.DatePublished, 
        Books.Author, 
        ROW_NUMBER() over (partition by Authors.AuthorID order by DatePublished desc) Rnum
    FROM Authors LEFT OUTER JOIN Books ON Authors.AuthorID = Books.Author
)x WHERE Rnum=1