You can do this with the second argument to the where function. I added an example here: https://github.com/r0man/sqlingvo/blob/master/test/sqlingvo/test/core.clj#L24
On Saturday, July 6, 2013 4:02:23 PM UTC+2, Carlo wrote: > > This is a fairly restricted composition, though: > > (def triangles (compose (select [:color :num_sides] (from :shapes)) > (where '(= :num_sides 3)))) > (def green-triangles (compose triangles > (where '(= :color "green")))) > (sql green-triangles) > ;=> ["SELECT color, num_sides FROM shapes WHERE (color = ?)" "green"] > > We've lost our `num_sides` selection, so now our query is wrong. "Last > clause wins" means you have to be aware of the previous ones to ensure you > don't obliterate them when "composing". > > The same example in `clojure-sql`: > > (def triangles (-> (table :shapes) > (project [:color :num_sides]) > (select '(= :num_sides 3)))) > (def green-triangles (select triangles '(= :color :green))) > (deref green-triangles) > ;=> ["SELECT \"shapes2142\".\"color\" AS \"color\", > \"shapes2142\".\"num_sides\" AS \"num_sides\" FROM \"shapes\" AS > \"shapes2142\" WHERE ((\"shapes2142\".\"num_sides\" = 3) AND > (\"shapes2142\".\"color\" = ?))" "green"] > > On 6 July 2013 22:37, r0man <roman....@burningswell.com <javascript:>>wrote: > >> Composing queries is done via "compose". >> >> Take a look here: >> https://github.com/r0man/sqlingvo/blob/master/test/sqlingvo/test/core.clj#L16 >> >> >> On Saturday, July 6, 2013 5:46:06 AM UTC+2, Carlo wrote: >> >>> Hey Roman, >>> >>> The issue that I see with `sqlingvo`, and the thing which I was trying >>> to solve for myself, is that it doesn't compose well. Unless I'm missing >>> something, you have to generate the entire query in the one `sql` form. To >>> me, this is a big restriction and was the number one thing I was trying to >>> fix with `clojure-sql`. >>> >>> The basic sort of thing I want to be able to do is this: >>> >>> (def users (-> (table :users) (project [:id :person :username]))) >>> (def people (-> (table :people) (project [:id :first-name]))) >>> >>> (def combined-query (-> people >>> (rename {:id :person}) >>> (join users) >>> (project [:username :first-name]))) >>> >>> So now in queries I can use `people`, `users` and `combined-query` in >>> the same way. The only difference in terms of how I can compose them is >>> that they expose different fields (`users` exposes [:id, :person, >>> :username], `people` exposes [:id :first-name], `combined-query` exposes >>> [:username :first-name]). In this example it's not completely obvious why >>> this would be beneficial, but it means that I can change `users`, for >>> instance, to also have a `(select '(= :deleted false)` in its definition >>> and no other code has to change. They will all join/query against the users >>> where `deleted` is false without any other modifications of code. >>> >>> This freedom of composition is what you have in relational algebra, and >>> what I was trying to get in Clojure as well. All the naming of tables and >>> field aliases and everything is handled by the library, so you only have to >>> worry about constructing the queries. Unfortunately SQL provides a number >>> of operations outside of the relational algebra model (grouping, sorting, >>> take/drop), so they've been "tacked on" as a bit of an afterthought and >>> could probably use some improvement. >>> >>> Looking at `sqlingvo` did show up a mistake that I made in how I was >>> dealing with sorts, though, so thanks for that! I think our libraries just >>> have fairly different concerns at the moment. >>> >>> Carlo >>> >>> >>> On 5 July 2013 20:59, r0man <roman....@burningswell.**com> wrote: >>> >>>> Hi Carlo, >>>> >>>> if you'are looking for generating more complex SQL there's also: >>>> >>>> https://github.com/r0man/**sqlingvo <https://github.com/r0man/sqlingvo> >>>> >>>> Roman. >>>> >>>> On Wednesday, July 3, 2013 10:48:07 AM UTC+2, Carlo wrote: >>>>> >>>>> Hey guys! >>>>> >>>>> I've been working on a small library to make writing SQL queries a >>>>> little bit easier. It's along the same lines as ClojureQL, but takes a >>>>> different approach and compiles into quite different SQL in the end. >>>>> >>>>> At the moment it's quite immature, but it should be able to support >>>>> any queries which can be expressed in relational algebra. There will be >>>>> some SQL queries which can't be expressed in clojure-sql, but hopefully >>>>> there won't be too many of those. A greater limitation is that at the >>>>> moment the SQL generation is specific to the PostgresSQL database >>>>> (although >>>>> any contributions for other databases are welcome!). >>>>> >>>>> Dependency vector: [clojure-sql "0.1.0"] >>>>> Repository: >>>>> https://bitbucket.org/czan/**clo**jure-sql<https://bitbucket.org/czan/clojure-sql> >>>>> Clojars link: >>>>> https://clojars.org/clojure-**sq**l<https://clojars.org/clojure-sql> >>>>> >>>>> Let me know what you think! >>>>> >>>>> Carlo >>>>> >>>> -- >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Clojure" group. >>>> To post to this group, send email to clo...@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+u...@**googlegroups.com >>>> >>>> For more options, visit this group at >>>> http://groups.google.com/**group/clojure?hl=en<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+u...@**googlegroups.com. >>>> >>>> For more options, visit >>>> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out> >>>> . >>>> >>>> >>>> >>> >>> -- >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com<javascript:> >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> 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+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- -- 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.
