<?php
/*********************************************
* step 2
* - get_products_by_category($category_id)
**********************************************/
function get_products_by_category($category_id) {
    global $db;
    $query = "SELECT * FROM products
              WHERE products.categoryID = '$category_id'
              ORDER BY productID";
    $products = $db->query($query);
    return $products;
}

?>