Re: Limit # of recs on inner join?
От | Richard Broersma Jr |
---|---|
Тема | Re: Limit # of recs on inner join? |
Дата | |
Msg-id | 195966.8694.qm@web31808.mail.mud.yahoo.com обсуждение исходный текст |
Ответ на | Limit # of recs on inner join? (Josh <josh@globalherald.net>) |
Список | pgsql-sql |
SELECT DISTINCT ON ( B.book_id, B.title ) B.book_id, B.title, A.Author FROM Books AS B INNER JOIN Authors AS A ON A.book_id = B.book_id; --- On Mon, 12/31/07, Josh <josh@globalherald.net> wrote: > From: Josh <josh@globalherald.net> > Subject: [SQL] Limit # of recs on inner join? > To: pgsql-sql@postgresql.org > Date: Monday, December 31, 2007, 10:52 AM > I want to limit the number of records returned by an inner > join. > > Suppose I have a table of Books: > > book_id > title > > And, a table of authors: > > book_id > author_name > > Now, suppose I want to get book + author, but I only want > one author for > books with multiple authors. Traditionally, I'd do > something like: > > select books.book_id, books.title, authors.author_name > from books > inner join authors on authors.book_id = books.book_id > where books.book_id = ? > > This might return: > > 1 A Cat In The Hat Dr. Seuss > 1 A Cat In The Hat Dr. Seuss' Partner > > Instead, I just want: > > 1 A Cat In The Hat Dr. Seuss > > How can I limit the inner join? > > Cheers, > -J > > > ---------------------------(end of > broadcast)--------------------------- > TIP 5: don't forget to increase your free space map > settings
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