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;;  Copyright (c) Stephen C. Gilardi. All rights reserved.
;;  The use and distribution terms for this software are covered by the
;;  Common Public License 1.0 (http://opensource.org/licenses/cpl.php)
;;  which can be found in the file CPL.TXT at the root of this distribution.
;;  By using this software in any fashion, you are agreeing to be bound by
;;  the terms of this license.
;;  You must not remove this notice, or any other, from this software.
;;
;;  sql.clj
;;
;;  A Clojure interface to sql databases via jdbc
;;
;;  See clojure.contrib.sql.test for an example
;;
;;  scgilardi (gmail)
;;  23 April 2008

(ns clojure.contrib.sql
  (:import
   (java.sql DriverManager Connection PreparedStatement ResultSet)))

(defn get-connection
  "Attempts to get a connection to a database via a jdbc URL"
  [subprotocol db-name]
  (let [url (str "jdbc:" subprotocol ":" db-name)]
    (DriverManager/getConnection url)))

(defmacro with-connection
  "Evaluates body in the context of a connection to a database. Any updates
  are committed as one transaction after evaluating body or rolled back on
  any uncaught exception."
  [con init & body]
  `(with-open ~con ~init
     (try
      (.setAutoCommit ~con false))
      ~@body
      (.commit ~con)
      (catch Exception e#
             (.rollback ~con)
             (throw (Exception. "transaction rolled back" e#)))))

(defn execute-commands
  "Executes a sequence of SQL commands that do not return results"
  [con commands]
  (with-open stmt (.createStatement con)
    (doseq cmd commands
      (.addBatch stmt cmd))
    (.executeBatch stmt)))

(defn execute-prepared-statement
  "Executes a prepared statement with a sequence of parameter sets"
  [con sql sets]
  (with-open stmt (.prepareStatement con sql)
    (doseq set sets
      (doseq [index value] (map vector (iterate inc 1) set)
        (.setObject stmt index value))
      (.addBatch stmt ))
    (.executeBatch stmt)))

(defmacro with-query-results
  "Executes a query and then evaluates body repeatedly with rec bound to
  each of the generated results in turn"
  [rec con sql & body]
  `(with-open stmt# (.prepareStatement ~con ~sql)
     (with-open rset# (.executeQuery stmt#)
       (doseq ~rec (resultset-seq rset#)
         ~@body))))