如何在Clojure中訪問SQLite數據庫？

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

你必須從with-query-results宏中實際返回一些東西。 因為seq綁定到results是懶惰的，讓我們消耗它：

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

這是使用clojure.contrib.sql時的常見模式，不依賴於SQLite JDBC適配器。

順便說一句，我從來沒有必須手動執行(Class/forName driver-class-str) ，這顯然是你的Java習慣。 驅動程序被加載到contrib.sql的引擎蓋下。