PHP MySQL 購物車程式執行個體

<?
if(!$session && !$scid) {
$session = md5(uniqid(rand()));
SetCookie("scid", "$session", time() 14400);
} /* last number is expiration time in seconds, 14400 sec = 4 hrs */
class Cart {
function check_item($table, $session, $product) {
$query = "SELECT * FROM $table WHERE session='$session' AND product='$product' ";
$result = mysql_query($query);
if(!$result) {
return 0;
}
$numRows = mysql_num_rows($result);
if($numRows == 0) {
return 0;
} else {
$row = mysql_fetch_object($result);
return $row->quantity;
}
}
function add_item($table, $session, $product, $quantity) {
$qty = $this->check_item($table, $session, $product);
if($qty == 0) {
$query = "INSERT INTO $table (session, product, quantity) VALUES ";
$query .= "('$session', '$product', '$quantity') ";
mysql_query($query);
} else {
$quantity = $qty;
$query = "UPDATE $table SET quantity='$quantity' WHERE session='$session' AND ";
$query .= "product='$product' ";
mysql_query($query);
}
}
function delete_item($table, $session, $product) {
$query = "DELETE FROM $table WHERE session='$session' AND product='$product' ";
mysql_query($query);
}
function modify_quantity($table, $session, $product, $quantity) {
$query = "UPDATE $table SET quantity='$quantity' WHERE session='$session' ";
$query .= "AND product='$product' ";
mysql_query($query);
}
function clear_cart($table, $session) {
$query = "DELETE FROM $table WHERE session='$session' ";
mysql_query($query);
}
function cart_total($table, $session) {
$query = "SELECT * FROM $table WHERE session='$session' ";
$result = mysql_query($query);
if(mysql_num_rows($result) > 0) {
while($row = mysql_fetch_object($result)) {
$query = "SELECT price FROM inventory WHERE product='$row->product' ";