Rules for shopping cart items

[NoBullMan]

Hi,
I would like to create a shopping cart and associate some rules with some of the items available for sale. For example, if x number of item A is selected, then an additional item B needs to be added to the cart. Also, some items might have a pre-requisite items (cannot add item A unless item B is already on the cart).
I would appreciate it if youcould give me some idea as how to approach this. I have setup the itmes in a MySQL database.

Also, while testing somethng, I noticed that when I use the "unset" function to remove an item from the cart (associative array), subsequent searches of the cart indicate the item is still there, even though displaying the cart (which goes through each item in the array) does not display the removed item! WHat I mean is, when I go through the array to diplay the items listed in it, the removed item does not show up, when I use the same method to search if the item is in the cart, it returns true.

Thanks alot.

[planetsim]

Well im not going to give you a database structure, but id imagine you'd require two tables

One table with the Product the second table related to the product which will then have in for that product maybe a single record for each extra requirement. You can do this in one table but itd be very messy