如何在Clojure中访问SQLite数据库？

发布时间：2020-12-12 18:59:19 所属栏目：百科来源：网络整理

导读：(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.JD

(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
    ))

解决方法

你必须从with-query-results宏中实际返回一些东西.因为seq绑定到结果是懒惰的,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.

顺便说一句,我从来没有必须手动执行(Class / forName driver-class-str),这显然是你的Java习惯.驱动程序被加载到contrib.sql的引擎盖下.

（编辑：李大同）

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