getUniqueCode()

<?php

// how to use
// echo $this->getUniqueCode();

function getUniqueCode() {
    $start = 1;
    $limit = 100;
    $query = "SELECT unique_code FROM orders ORDER BY id DESC";
    $fetch = $this->db->query( $query )->row();
    $code = $fetch->unique_code;
    return $code < $limit ? $code + 1 : $start;
}