codeigniter中的多个数据库

我试图在ci中实现多个数据库。我的代码在这里:

//database.php
$active_group = "default";
$active_record = TRUE;

$db['default']['hostname'] = "localhost";
$db['default']['username'] = "root";
$db['default']['password'] = "root";
$db['default']['database'] = "ravelex";
$db['default']['dbdriver'] = "mysql";
$db['default']['dbprefix'] = "rvx_";
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci";

$db['smf']['hostname'] = "localhost";
$db['smf']['username'] = "root";
$db['smf']['password'] = "root";
$db['smf']['database'] = "smf";
$db['smf']['dbdriver'] = "mysql";
$db['smf']['dbprefix'] = "smf_";
$db['smf']['pconnect'] = TRUE;
$db['smf']['db_debug'] = TRUE;
$db['smf']['cache_on'] = FALSE;
$db['smf']['cachedir'] = "";
$db['smf']['char_set'] = "utf8";
$db['smf']['dbcollat'] = "utf8_general_ci";

模型是

//user_model.php
class user_model extends Model {
    private $ravelex_db;
    function user_model() {
        parent::Model();
        $this->ravelex_db = $this->load->database('default', TRUE);
    }

    function find_all() {
        print_r($this->ravelex_db);
        $q = $this->ravelex_db->get('users');
        return $q->result();
    }
}

//smf_user_model.php
class smf_user_model extends Model {
    private $smf_db;

    function smf_user_model() {
        parent::Model();
        $this->smf_db = $this->load->database('smf', TRUE);
    }

    function find_all() {
        $q = $this->smf_db->get('members');
        return $q->result();
    }
}

控制器测试仪

    class mutipledb extends Controller {

    function mutipledb() {
        parent::Controller();
        $this->load->database();
        $this->load->model('user_model');
        $this->load->model('smf_user_model');
    }

    function index() {
        print_r($this->user_model->find_all());
        print_r($this->smf_user_model->find_all());
    }
}

有一些错误,第一个数据库使用第二个数据库名。但它仍然使用前缀。

错误是

A Database Error Occurred
Error Number: 1146
Table 'smf.rvx_users' doesn't exist
SELECT * FROM (`rvx_users`)