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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)
;; Created 2 April 2008
(ns clojure.contrib.sql
(:import
(java.sql DriverManager Connection PreparedStatement ResultSet)))
(defn connection
"Attempts to get a connection to a database via a jdbc URL"
[subprotocol db-name]
(DriverManager/getConnection (format "jdbc:%s:%s" subprotocol db-name)))
(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 do-commands
"Executes SQL commands that do not return results"
[con & commands]
(with-open stmt (.createStatement con)
(doseq cmd commands
(.addBatch stmt cmd))
(.executeBatch stmt)))
(defn do-prepared
"Executes a prepared statement with 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)))
(defn create-table
"Creates a table given a name and column specifications"
[con name & cols]
(do-commands con
(format "create table %s (%s)"
name
(apply str (interpose "," cols)))))
(defn drop-table
"Drops a table give its name"
[con name]
(do-commands con
(format "drop table %s" name)))
(defn insert-values
"Inserts values into columns of a table. Columns is a seq of column
names (as strings) and each value is a seq of values for those
columns. To insert complete rows (all columns), use insert-rows"
[con table columns & values]
(let [count (count (first values))
template (apply str (interpose "," (replicate count "?")))
cols (if (seq columns)
(format "(%s)" (apply str (interpose "," columns)))
"")]
(apply do-prepared
con
(format "insert into %s %s values (%s)" table cols template)
values)))
(defn insert-rows
"Inserts complete rows into a table. Each row is a seq of values for
each of the table's columns in order."
[con table & rows]
(apply insert-values con table nil rows))
(defmacro with-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))))
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