>select cust_id from customer where cust_id in
> (select cust_id from purchased
> where item_id = soap and cust_id in
> (select cust_id from purchased
> where item_id = towels and cust_id in
> (select cust_id from purchased where item_id = toothbrush)
> )
> )

Albert,

There could be any number of items selected from a multilist. Looks like this could get long and ugly with 20 items.