increasing the quantity in cart when add the same product again.

hi everybody,

i want to increase the product quantity by 1 when the customer adds the same product again in the cart. this is my PHP code:

<?php include("connection.php"); ?>
<?php
session_start();
$sessionid = session_id();
$code = $_POST["code"];
$model = $_POST["model"];
$descr = $_POST["descr"];
$pricer = $_POST["pricer"];
$qty = $_POST["qty"];
$cart = $_POST["cart"];
If($qty == "") $qty=1;
?>

<?php
if ( !empty($cart) ) {
  switch($cart) {
    case "add":
      $sql= "INSERT INTO cart (sessionid, code, model, descr, pricer, qty) VALUES ('$sessionid','$code','$model','$descr','$pricer','$qty')";
      break;
    case "del":
      $sql= "DELETE FROM cart WHERE code='$code'";
      break;
    case "upd":
      $sql= "UPDATE cart SET qty='$qty' WHERE code='$code'";
      break;
  }
  if ( !empty($sql) ) {
    $res= mysql_query($sql);
    // handle any query errors here
  }
}

$result = mysql_query("SELECT * FROM cart WHERE sessionid='".$sessionid."' ORDER BY pricer");

mysql_close($con);
?>

PHP:

i have attached the cart.php if anybody wants to take a look. some words are in greek. just ignore it.

thanks in advance.

 

If you want a quick hack, try this:

session_start();
$sessionid = session_id();
$code = $_POST["code"];
$model = $_POST["model"];
$descr = $_POST["descr"];
$pricer = $_POST["pricer"];
$qty = $_POST["qty"];
$cart = $_POST["cart"];
If($qty == "") $qty=1;
?>

//NEW UPDATE HACK

$if_ud_query = mysql_query("SELECT qty FROM cart WHERE sessionid = '$sessionid' AND code = '$code'");

if(mysql_num_rows($if_ud_query) > 0)
{
//the item is already in the cart
$cart = 'upd';
}

//END NEW UPDATE HACK

<?php
if ( !empty($cart) ) {
  switch($cart) {
    case "add":
      $sql= "INSERT INTO cart (sessionid, code, model, descr, pricer, qty) VALUES ('$sessionid','$code','$model','$descr','$pricer','$qty')";
      break;
    case "del":
      $sql= "DELETE FROM cart WHERE code='$code'";
      break;
    case "upd":
      $sql= "UPDATE cart SET qty='$qty' WHERE code='$code'";
      break;
  }

PHP:

 

it doesn't work my friend. when i add the same product again, the quantity isn't increased. the update and delete sql queries is not working. only the insert query is working.