Add:
ORDER BY ProductUpdateDate DESC
to the end of the query:
SELECT *, (ProductStock - (SELECT Coalesce(Sum(DetailQuantity),0)
FROM orderdetails INNER JOIN orders ON OrderID = DetailOrderID
WHERE DetailProductID = ProductID AND OrderDate > ProductUpdateDate)) AS NumLeft FROM products LEFT OUTER JOIN productcategories ON ProductCategoryID = CategoryID WHERE ProductLive <> 0
ORDER BY ProductUpdateDate DESC