Marnen Laibow-Koser wrote: > [...] >>> [outer SELECT and JOIN as above] >>> ORDER BY article.id, version.created_at desc >>> GROUP BY article.id >>> [further JOINs may be necessary in some DBs, but the principle holds] >> >> How does this ensure that I get the latest version? > > Sorry, I meant versions.updated_at desc in the order clause, not > created_at. And the way it works is this: the ORDER clause sorts the > versions by article ID, then by timestamp, ensuring that versions for > the same article are together with the newest first. Then the GROUP > clause returns only one record -- the first, ergo the newest -- for each > article ID.
Well, you learn something new every day! I found the Ambiguous Groups article on the Web and found that the behavior I thought was standard -- returning the first value in the case of multiple values -- is actually a MySQL quirk (ironic when you consider that I haven't used MySQL in years). Back to the drawing board. Best, -- Marnen Laibow-Koser http://www.marnen.org mar...@marnen.org Sent from my iPhone -- Posted via http://www.ruby-forum.com/. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-t...@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-talk+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
