MongoDB-CodeIgniter-Driver

下载地址：https://github.com/kyledye/MongoDB-CodeIgniter-Driver

1.  Add the mongo_db.php config file to your ./system/application/config directory and make the
appropriate changes to connect to your database

2. Copy the Mongo_db.php library file to your ./system/application/libraries directory
3. (optional) Add the library to your autoload.php file if you plan to frequently reference the library

创建配置文档：config/mongo.php

创建库文件：libraries/Mongo.php

实例：controllers/posts.php

这种方法倒是能连上mongodb数据库，但是我们想通过改CodeIgniter的数据库文件实现mongodb的扩展，

我没研究明白，who知道方法，要不就等我们杨哥帮我们实现了。