;; This sandbox carries no JDBC driver and no network, so no real
;; connection can be opened. The query itself, though, is only a
;; selection over rows - and rows in Clojure are ordinary data
(def country-language
  [{:code "RUS" :language "Russian"   :percentage 86.6}
   {:code "RUS" :language "Tatar"     :percentage 3.2}
   {:code "RUS" :language "Ukrainian" :percentage 1.3}
   {:code "USA" :language "English"   :percentage 86.2}])

;; select language, percentage from countrylanguage
;; where code = 'RUS' order by percentage desc
(def rows
  (->> country-language
       (filter #(= "RUS" (:code %)))
       (sort-by :percentage >)))

;; the first row
(println "first:" (:language (first rows)) (:percentage (first rows)))

;; and the ones that follow
(doseq [r (rest rows)]
  (println (:language r) ":" (:percentage r)))

;; with next.jdbc on the classpath the same query is one call:
;; (jdbc/execute! conn ["select language, percentage
;;                       from countrylanguage where code = 'RUS'"])