如何在Clojure中访问SQLite数据库？

Question

(ns db-example
   (:use [clojure.contrib.sql :only (with-connection with-query-results)] )
   (:import (java.sql DriverManager)))

;; need this to load the sqlite3 driver (as a side effect of evaluating the expression)
(Class/forName "org.sqlite.JDBC")

(def +db-path+  "...")
(def +db-specs+ {:classname  "org.sqlite.JDBC",
                 :subprotocol   "sqlite",
                 :subname       +db-path+})

(def +transactions-query+ "select * from my_table")

(with-connection +db-specs+
  (with-query-results results [+transactions-query+]
    ;; results is an array of column_name -> value maps
    ))

Answer 1

你必须从with-query-results宏中返回一些东西.因为seq绑定results是懒惰的,让我们消耗它:

(with-connection +db-specs+  
   (with-query-results results [+transactions-query+]  
     (doall results)))  

这是使用clojure.contrib.sql时的常见模式,不依赖于SQLite JDBC适配器.

顺便说一下,我从来不必(Class/forName driver-class-str)手动操作,这显然是你的Java习惯.驱动程序被加载到contrib.sql的引擎盖下.