[carcabob]

Novice Question: How can you have a relational database at all without foreign keys?

In other words, if your tables aren't referencing other tables, how do you perform JOINS for your queries? From my limited experience, they seem pretty essential for most databases. Or is the article just talking about foreign key CONSTRAINTS and cascading UPDATES and DELETES, rather than literally talking about the values stored in foreign key columns?

If anyone can explain, I would greatly appreciate it.

[sseagull]

Foreign keys are really just constraints - the row referred to by the FK must exist, and the database will ensure that. That is the basic idea. Cascading, etc are just useful features on top.

While FKs and JOINs often go hand in hand, JOINs actually do not require foreign keys or any other constraint. You can join any table and column that you want regardless of FK or index or whatever (although you have to be careful about performance).