public function save(User_infoModel $user)
{
$query = 'INSERT INTO user_info(user_id, gender, first_name, last_name, email)
VALUE (?, ?, ?, ?, ?)';
$param = [$user->getUserId(), $user->getGender(), $user->getFirstName(), $user->getLastName(), $user->getEmail()];
$this->db->query($query, $param);
return $this->db->row();
}