Good article and thank you.
I found it amusing the discussion, cough, on terms stated in article and math representations. Sigh... I guess some folks have nothing better to do than to pick away at what others are trying to contribute.
Maybe this is in another article, but would like to see comparison between INTERSECT and INNER JOIN w/wo/DISTINCT. When is it appropriate to use one versus the other with regards to performance and readability.
Thank you again.