shopping cart explain please?

[ceanth]

Hi all i have a shopping cart, which uses db.php which contains the database details, db.php also contains:

function GetCartId()
{

if(isset($_COOKIE["cartId"]))
{
	return $_COOKIE["cartId"];
}
else
{

session_start();
setcookie("cartId", session_id(), time() + ((3600 * 24) * 30));
return session_id();
	}
}

Now this is all in db.php along with the mysql_link and all of that.

db.php is refered to when search results are done, and in cart.php.

Now the coding for cart.php for adding an item is:

$result = mysql_query("select count(*) from cart where cookieId = '" . GetCartId() . "' and itemId = $itemId");

There is also a table called cart which is as follows:

create table cart
(
cartId int auto_increment not null,
cookieId varchar(50),
itemId int,
qty int,
primary key(cartId),
unique id(cartId)
);

Now could someone please explain to me how this setup actually works(im a newbie to this and it will help my understanding and also help in making advances to this setup)?

Many Thanks

ceanth

[barand]

The first bit saves an id in a cookie on the users PC. The cookie will expire after 30 days. Until then, when the user goes to the site, the id can be read from the cookie and his database records accessed using the saved id.

The code for adding an item is incomplete. The bit shown here is seeing if there already is an item of that type already in the cart for that user. Presumably it goes on to update the quantity if there is one or add a new record if there isn not.

hth