Re: Curious SQL question
From: Neo <neo55592_at_hotmail.com>
Date: 5 Jan 2007 10:19:34 -0800
Message-ID: <1168021174.237093.190700_at_i15g2000cwa.googlegroups.com>
Date: 5 Jan 2007 10:19:34 -0800
Message-ID: <1168021174.237093.190700_at_i15g2000cwa.googlegroups.com>
> 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 - 19:19:34 CET