Practical SQL Handbook, The: Using SQL Variants, Fourth Edition

Using the Cartesian Product

Valid joins are essential to producing comprehensible multitable query results, unless one of the tables contains a single row—perhaps a system variable or a stored value. In that case, you can use a Cartesian product between two tables without fear. For example, test3 contains the current tax rate.

SQL

create table test3
(rate decimal not null,
date_start date not null default current date)
[table created]
insert test3 (rate)
values (.08)
[1 row]

You can use test3 with titles without a join to calculate the base-plus-tax price of books.

SQL

select title_id as Book, price as BasePrice, price + ( price * rate)
as TaxPrice
from titles, test3 where type = 'business' order by title_id Book BasePrice TaxPrice ====== ========== ...