Readers of my book OCA Oracle Database SQL Certified Expert Exam Guide (Exam 1Z0-047) are familiar with The Cartesian Product Challenge!
On page of 332 of the book, I included this blurb about CROSS JOINS and Cartesian products:
A few things to consider with Cartesian products:
- They are mentioned in the certification exam objectives.
- There are generally considered to be a “mistake” in professional applications.
- If you ever find a reasonable use for one, please let me know at email@example.com. The first person to notify me of such an application will win $10 in cash from me.
That being said, they are on the exam, so know the term and the functionality.
Since the publication of the book, I’ve received a bunch of outstanding emails from readers, and I’ve been collecting them and considering them.
I announced the winner of the Cartesian Product Challenge at Oracle Open World: