<?php

protected $active_group;
protected $db2;

public function __construct() {

    parent::__construct();
    $this->connect();
}

$this->db->close();
}

public function connect($active_group = 'default'){

    $this->active_group = $active_group;
    $db = $this->load->database($active_group, TRUE);
    $this->db = $db;

     $db['second'] = array(
                             'dsn'   => '',
                             'hostname' => 'localhost',
                             'username' => 'root',
                             'password' => '',
                             'database' => 'nomedobanco',
                             'dbdriver' => 'mysqli',
                             'dbprefix' => '',
                             'pconnect' => FALSE,
                             'db_debug' => (ENVIRONMENT !== 'production'),
                             'cache_on' => FALSE,
                             'cachedir' => '',
                             'char_set' => 'utf8',
                             'dbcollat' => 'utf8_general_ci',
                             'swap_pre' => '',
                             'encrypt' => FALSE,
                             'compress' => FALSE,
                             'stricton' => FALSE,
                             'failover' => array(),
                             'save_queries' => TRUE
    );

      //$db2 = $this->load->database('second', TRUE);
    $this->db2 = $db;
}