too long

Question

Can someone tell me, in this query how to do the echo if the quantity is more than stock?

$updatequery =
    "UPDATE products SET
        stock =
            CASE WHEN stock >= '$quantity' THEN
                (stock-'$quantity')
            ELSE
                stock
            END
    WHERE product = '$product' " ;

I tried something like this but it doesn't work!

if (!$updatequery) {
    echo " We are sorry! The available stock of selected product ($stock units) in not enough ";
} else {
    echo "Hello $username! You ordered $product with quantity: $stock succesfully";
}

Answer 1

Try this:

$updatequery = "
    UPDATE `products`
    SET `stock` = `stock` - ".intval($quantity)."
    WHERE `product` = '".appropriate_escaping_function($product)."'
      AND `stock` >= ".intval($quantity)."
";

Then, check the affected_rows function (can't tell you exactly what function without knowing what library you're using, but a quick search should find it). If it's zero, then either the product wasn't found (which you should already know before even trying to update) or it failed the stock >= quantity check.