function getBalanceByID()
{
$this->db->select_sum('amount');
$query = $this->db->get('cms_operations');
return $query->result();
}
public function index()
{
$this->load->view('v_header');
$this->load->model('mdl_billing');
$data['query'] = $this->mdl_billing->getBalanceByID();
$this->load->view('v_billing', $data);
$this->load->view('v_billing');
$this->load->view('v_footer');
}
????