problem1.clj

(require '[clojure.java.jdbc :as jdbc])

(def db-spec
  {:dbtype "postgresql"
   :dbname "jdbctest"
   :user "your_pg_user"
   :password "your_pg_password"})

(doc jdbc/execute!)
;; => -------------------------
;; => clojure.java.jdbc/execute!
;; => ([db sql-params] [db sql-params opts])
;; =>   Given a database connection and a vector containing SQL (or PreparedStatement)
;;      followed by optional parameters, perform a general (non-select) SQL operation.
;;      The :transaction? option specifies whether to run the operation in a
;;      transaction or not (default true).
;;      If the :multi? option is false (the default), the SQL statement should be
;;      followed by the parameters for that statement.
;;      If the :multi? option is true, the SQL statement should be followed by one or
;;      more vectors of parameters, one for each application of the SQL statement.
;;      If :return-keys is provided, db-do-prepared-return-keys will be called
;;      instead of db-do-prepared, and the result will be a sequence of maps
;;      containing the generated keys.
;;      If there are no parameters specified, executeUpdate will be used, otherwise
;;      executeBatch will be used. This may affect what SQL you can run via execute!

(jdbc/execute!
 db-spec
 ["insert into foo (x, y) values (?, ?), (?, ?)" "x1" "y1" "x2" "y2"]
 {:return-keys true})
;; => {:x "x1", :y "y1"}

(jdbc/execute!
 db-spec
 ["insert into foo (x, y) values (?, ?)" ["x1" "y1"] ["x2" "y2"]]
 {:return-keys true :multi? true})
;; => ({:x "x1", :y "y1"} {:x "x2", :y "y2"})

;;; My expectation is
(jdbc/execute!
 db-spec
 ["insert into foo (x, y) values (?, ?), (?, ?)" "x1" "y1" "x2" "y2"]
 {:return-keys true})
;; => ({:x "x1", :y "y1"} {:x "x2", :y "y2"})

problem2.clj

(jdbc/execute! db-spec ["insert into foo (x, y) values (?, ?)" "x1" "y1"] {:return-keys ["x"]})
;; => {:x "x1", :y "y1"}

;;; My expectation is
(jdbc/with-db-connection [db db-spec]
  (let [stmt (-> (jdbc/db-find-connection db)
                 (jdbc/prepare-statement "insert into foo (x, y) values (?, ?), (?, ?)" {:return-keys ["x"]}))]
    (#'jdbc/dft-set-parameters stmt ["x1" "y1" "x2" "y2"])
    (.executeUpdate stmt)
    (jdbc/result-set-seq (.getGeneratedKeys stmt))))
;; => ({:x "x1"} {:x "x2"})