Clojure-JVM上的函数式编程语言(17)数据库 作者: R. Mark Volkmann

原帖地址：http://java.ociweb.com/mark/clojure/article.html#Databases

作者：R. Mark Volkmann  

译者：RoySong

数据库

    Clojure Contrib 中的sql库简化了对关系型数据库的访问，它支持事务提交回滚、预声明、创建和删除表、插入

更新删除记录和运行条件查询。下面的例子连接到一个Postgres数据库并运行了查询。注释中增加了对mysql数据库

的支持。

(use 'clojure.contrib.sql)

(let [db-host "localhost"
      db-port 5432 ; 3306
      db-name "HR"]

  ; The classname below must be in the classpath.
  (def db {:classname "org.postgresql.Driver" ; com.mysql.jdbc.Driver
           :subprotocol "postgresql" ; "mysql"
           :subname (str "//" db-host ":" db-port "/" db-name)
           ; Any additional map entries are passed to the driver
           ; as driver-specific properties.
           :user "mvolkmann"
           :password "cljfan"})

  (with-connection db ; closes connection when finished
    (with-query-results rs ["select * from Employee"] ; closes result set when finished
      ; rs will be a non-lazy sequence of maps,
      ; one for each record in the result set.
      ; The keys in each map are the column names retrieved and
      ; their values are the column values for that result set row.
      (doseq [row rs] (println (row :lastname))))))

    clj-record库中提供了持久化的API，这个是从ROR的 ActiveRecord库获得灵感的。要获得更多的信息，请访问

http://github.com/duelinmarkers/clj-record/tree/master 。