When I was learning Microsoft Access, many years ago, I didn't really understand joins. So I did a cross join with no where condition. And the machine (Windows

When I was learning Microsoft Access, many years ago, I didn't really understand joins. So I did a cross join with no where condition. And the machine (Windows XP) just sat there, and eventually locked up. So I rebooted, and tried it again. Same result. Eventually I figured it out.