Re: Curious SQL question

> select distinct orders.customer_id, products.product_id
> from orders, products
> minus
> select distinct customer_id, product_id
> from products;
>
> The first select esablishes a "universe of discourse" for the query by
> joining every customer with every product. The second select excludes
> products that a customer did buy.

The above SQL makes the solution easy to understand (should the last line of the SQL be orders instead of products). Assuming the following:

set A = {shampoo, soap, bread, wine}
set B = {shampoo, soap, bread}
set C = {wine}

What is the most appropriate name of the function that does the following:

C = f (A, B);

Is it NAND, NOT INTERSECTION, NOT IN? And should the order of the inputs (A, B) matter? Received on Fri Jan 05 2007 - 12:19:34 CST