Thanks, Carlo. Even without the documentation, I'm beginning to get the hang of the DSL. I should have guessed that '(and...) would have done the trick. I'd like to put a request in for using a map or a vector of pairs as an alternative since it's easier to construct those.
One more request: Support for SELECT DISTINCT. Using 0.1.0, I could get around the lack of DISTINCT by using GROUP BY but with the new projection argument, that becomes inconvenvient. In our project, we do a ton of programmatic SQL manipulation and your library makes it much easier. Thanks for contribution! On Wednesday, November 20, 2013 7:54:19 PM UTC-8, Carlo wrote: > > Hi Mark! > > On Wed, Nov 20, 2013 at 01:11:11PM -0800, Mark wrote: > > I'm using the 2.0 snapshot. How should I express a join on multiple > > columns, ie > > SELECT blah FROM t1 JOIN t2 ON (t1.a=t2.b) AND (t1.c=t2.d) ? > > Something like this should work: > > (let [t1 (-> (table :t1) > (project [:a :c])) > t2 (-> (table :t2) > (project [:b :d]))] > (join t1 t2 :on `(and (= :a :b) > (= :c :d)))) > > If you've got shared attributes this won't work for you, though, because > then there's an ambiguity about whether to use a natural join (ie. > joining on equality of shared attributes) or your join condition (which > will leave an ambiguity about which shared attribute to use). In that > case you can use something like this: > > (let [t1 (-> (table :t1) > (project [:a :b])) > t2 (-> (table :t2) > (project [:a :c]))] > (join (rename t1 (as-subobject :t1)) > (rename t2 (as-subobject :t2)) > :on `(and (= :t1.a :t2.c) > (= :t2.a :t1.b)))) > > > Sorry about the lack of documentation for this. I'm working on it, but > I've been quite busy/distracted lately. Hopefully I'll have some more > time to get back to it soon. > > Carlo > -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
