Как много строк будет возвращено (тестирование)?

CREATE TABLE #A (Author Varchar(20), Location Varchar(20))

INSERT INTO #A(Author,Location)
VALUES
('Job', 'NY' ),
('Jim', 'MD' ),
('Job', 'NY' ),
(NULL , NULL )

CREATE TABLE #B (Book Varchar(20),Author Varchar(20))

INSERT INTO #B(Book,Author)
VALUES
('A', 'Job' ),
('B', 'Jim' ),
('C', 'Job' ),
(NULL, NULL )

SELECT a.Author,b1.book,b2.Book, a.Location
FROM #A a
JOIN (SELECT Author,MAX(Book) MaxB, MIN(Book) MinB FROM #B GROUP BY Author) b0 ON b0.Author=a.Author
JOIN #B b1 ON b1.Author=b0.Author
JOIN #B b2 ON b2.Author=b0.Author

DROP TABLE #A
DROP TABLE #B

Ссылка на рубрику «Проверь себя»