When Item Is Purchased (Through Paypal), Subtract One Number From Stock

[davids_media]

I have somewhat of a dilemma.

 

When someone clicks on a Buy Now button and subsequently follows necessary steps to complete process of purchase, when that transaction is completed, in my product table, I want to subtract 1 from whatever value is in the field.

 

E.g. say product one is being purchased, prior to purchase in product table, there are 5 product one's in stock, when purchase is complete, subtract 1 from 5 (to get 4).

 

Here is my code

 

<?php
$title = "Like This Product, Buy It NOW!!!";
require ('includes/config.inc.php');
include ('./includes/header.html');
require (MYSQL);
include ('./includes/main.html');
if($id = isset($_GET['prodID']))
{
$query = "SELECT `prodID`, `product`, `prod_descr`, `image`, `price` FROM product WHERE `prodID`='{$_GET['prodID']}'";
$r = mysqli_query($dbc, $query);
$showHeader = true;
echo "<div id='right'>";
while($row = mysqli_fetch_array($r))
{
if($showHeader)
{
	    //Display category header
echo "<h1>" . "<span>" . "# " . "</span>" . $row['product'] .  "<span>" . " #" . "</span>" . "</h1>";
echo "<div id='item'>"; // div class 'item'
echo "<div class='item_left'>";
echo "<p id='p_desc'>";
echo $row['prod_descr'];
echo "</p>";
echo "<p>" . "<span>" . "&pound" . $row['price'] . "</span>" . "</p>";
echo "</div>";
echo "<div class='item_right'>";
echo "<img src='db/images/".$row['image']."' />";
$showHeader = false;
echo "</div>";
?>
<p>
<form target="paypal" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="7UCL9YCYYXL3J">
<input type="hidden" name="item_name" value="<?php echo $row['product']; ?>">
<input type="hidden" name="item_number" value="<?php echo $row['prodID']; ?>">
<input type="hidden" name="amount" value="<?php echo $row['price']; ?>">
<input type="hidden" name="currency_code" value="GBP">
<input type="image" src="https://www.sandbox.paypal.com/en_US/i/btn/btn_cart_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.sandbox.paypal.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>
</p>
<p>
<form name="_xclick" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="me@mybusiness.com">
<input type="hidden" name="currency_code" value="GBP">
<input type="hidden" name="item_name" value="<?php echo $row['product']; ?>">
<input type="hidden" name="amount" value="<?php echo $row['price']; ?>">
<input type="image" src="http://www.paypal.com/en_US/i/btn/btn_buynow_LG.gif" border="0" name="submit" alt="Make payments with PayPal - it's fast, free and secure!">
</form>
</p>
<?php
echo "</div>"; // End of div class 'item'
$strSQL = "SELECT prodID, product, price, image FROM product ORDER BY RAND() LIMIT 1"; 
$objQuery = mysqli_query($dbc, $strSQL) or die ("Error Query [".$strSQL."]");
while($objResult = mysqli_fetch_array($objQuery)) 
{
echo "<div class='love'>";
echo "<h6>Like this......you'll love this!!!</h6>";
echo "<ul>";
echo "<li>" . "<img src='db/images/" . $objResult['image'] . "' width='50' height='50' />" . "</li>";
echo "<br />";
echo "<li>" . "<a href='item.php?prodID={$objResult['prodID']}' title='{$objResult['product']}'>" . $objResult['product'] . "</a>" . " - " . "&pound" . $objResult['price'] . "</li>";
echo "</ul>";
echo "</div>";
}
}
}
?>
<?php
echo "</div>";
}
include ('./includes/footer.html');
?>

 

 

How is this achievable please?

[margaux]

once the transaction has completed successfully you can use an update

UPDATE product SET stock = stock-1 WHERE prodID=$_GET['prodID']

[Larry]

That's the right idea, although the value wouldn't be in GET and you'd want to make sure it's safe to use in a query anyway.

 

The admin scripts show how to do this once an order is completed. You'd just apply that same code after the purchase has gone through instead.