ci框架使用sum

$this->db->select_sum('sy_myb');
$this->db->where(array("uid" => $data["uid"], "addtime" => strtotime(date("Y-m-d"))));
$ordercount=$this->db->get("daily_tasks_log")->result_array();
$return["odtoady_myb"] = $ordercount[0]["sy_myb"];