So you have your database beautifully set up according to Codd. What do you need when you have to retrieve data from related tables? Most probably a JOIN operator, but which one?

From LEFT to RIGHT, when is it INNER and when OUTER? Is a CROSS JOIN something NATURAL? And why may ANTI yield more results than SEMI...? How and when do their buddies MERGE, HASH and NESTED LOOP get to participate?

We'll have demos for all of this on well-known databases. And if all that doesn't make your head dizzy enough, I might even throw in some CROSS and OUTER APPLY.