CodeIgniter中的数据库连接错误

我试图在本地机器中运行CodeIgniter，但我得到了这个错误

有人知道问题出在哪里吗？我在mac 上使用MAMP

ErrorException[致命错误]：无法使用提供的设置连接到数据库服务器。/文件名：core/Loader.php/行号：346APPPATH/controllers/home.php[9]

protected $os_platforms = NULL;
function __construct()
{
    parent::__construct();
    $this->load->model(strtolower(__CLASS__).'_model', 'model');
    $this->load->config('brandmgr', TRUE);
    $this->lang->load(strtolower(__CLASS__));
    $this->_auto_rootCrumb();
FCPATH/system/database/DB_driver.php [ 1197 ] » MY_Exceptions->show_error(arguments)
FCPATH/system/database/DB_driver.php [ 124 ] » CI_DB_driver->display_error(arguments)
FCPATH/system/database/DB.php [ 148 ] » CI_DB_driver->initialize()
FCPATH/system/core/Loader.php [ 346 ] » DB(arguments)
FCPATH/system/core/Loader.php [ 1171 ] » CI_Loader->database()
FCPATH/system/core/Loader.php [ 152 ] » CI_Loader->_ci_autoloader()
FCPATH/system/core/Controller.php [ 51 ] » CI_Loader->initialize()
APPPATH/core/MY_Controller.php [ 25 ] » CI_Controller->__construct()
APPPATH/controllers/home.php [ 9 ] » MY_Controller->__construct()
FCPATH/system/core/CodeIgniter.php [ 308 ] » Home->__construct()
FCPATH/index.php [ 214 ] » require_once(arguments)

提前感谢！

这是database.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
$active_group = ENVIRONMENT;
$active_record = TRUE;
$db['development']['hostname'] = 'localhost';
$db['development']['username'] = 'fake';
$db['development']['password'] = 'fake';
$db['development']['database'] = 'bmgr';
$db['development']['dbdriver'] = 'mysqli';
$db['development']['dbprefix'] = '';
$db['development']['pconnect'] = TRUE;
$db['development']['db_debug'] = TRUE;
$db['development']['cache_on'] = FALSE;
$db['development']['cachedir'] = '';
$db['development']['char_set'] = 'utf8';
$db['development']['dbcollat'] = 'utf8_general_ci';
$db['development']['swap_pre'] = '';
$db['development']['autoinit'] = TRUE;
$db['development']['stricton'] = FALSE;
$db['staging']['hostname'] = 'localhost';
$db['staging']['username'] = 'fake';
$db['staging']['password'] = 'fake';
$db['staging']['database'] = 'bmgr1';
$db['staging']['dbdriver'] = 'mysqli';
$db['staging']['dbprefix'] = '';
$db['staging']['pconnect'] = TRUE;
$db['staging']['db_debug'] = TRUE;
$db['staging']['cache_on'] = FALSE;
$db['staging']['cachedir'] = '';
$db['staging']['char_set'] = 'utf8';
$db['staging']['dbcollat'] = 'utf8_general_ci';
$db['staging']['swap_pre'] = '';
$db['staging']['autoinit'] = TRUE;
$db['staging']['stricton'] = FALSE;

添加了环境

define('ENVIRONMENT', 'development');
 *---------------------------------------------------------------
 * ERROR REPORTING
 *---------------------------------------------------------------

if (defined('ENVIRONMENT'))
{
switch (ENVIRONMENT)
{
    case 'development':
    case 'staging':
        error_reporting(E_ALL);
     ini_set('display_errors', 1);
    break;
    case 'testing':
    case 'production':
        error_reporting(0);
     ini_set('display_errors', 0);
    break;
    default:
        exit('The application environment is not set correctly.');
}
}