$db['default'] = array(
	'dsn'	=> '',
	'hostname' => 'localhost',
	'username' => 'root',
	'password' => '',
	'database' => 'default_db',
	'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
);

$db['internal'] = array(
	'dsn'	=> '',
	'hostname' => 'localhost',
	'username' => 'root',
	'password' => '',
	'database' => 'other_db',
	'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
);

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Sample extends CI_Model
{
	private $default;
	private $other;
	function __construct()
	{
		$this->load->library('m_db');
		$this->default=new M_db(); // For Default Group Database
		$this->other=new M_db('otherdb'); //For Other Group Database
	}
	
	function get_default($where=array(),$order="",$group_by='')
	{
		$d=$this->default->get_data('default_table',$where,$order,$group_by);
		return $d;
	}
	
	function get_other($where=array(),$order="",$group_by='')
	{
		$d=$this->other->get_data('other_table',$where,$order,$group_by);
		return $d;
	}
	
	function find_id($fieldDefaultID,$output='')
	{
		$s=array('ID'=>$fieldDefaultID);
		$item=$this->default->get_row('default_table',$s,$output);
		return $item;
	}
	
	function count_table()
	{
		$count=$this->default->count_data('default_table');
		return $count;
	}
	
	function insert_data($field1,$field2)
	{
		$d=array(
			'field1'=>$field1,
			'field2'=>$field2,
		);
		if($this->default->add_row('default_table',$d)==TRUE)
		{
			return true;
		}else{
			return false;
		}
	}
	
	function edit_data($primaryKey,$field1,$field2)
	{
		$s=array(
			'ID'=>$primaryKey
		);
		$d=array(
			'field1'=>$field1,
			'field2'=>$field2,
		);
		if($this->default->edit_row('default_table',$d,$s)==TRUE)
		{
			return true;
		}else{
			return false;
		}
	}
	
	function delete_row($primaryKey)
	{
		$s=array(
			'ID'=>$primaryKey
		);
		if($this->default->delete_row('default_table',$s)==TRUE)
		{
			return true;
		}else{
			return false;
		}
	}
	
}