I thought it was a good introductory article for those interested in understanding data structure who do not have a doctorate in applied mathematics.

I especially liked the use of the Venn diagrams for visual clarity and even though I have been a DBA for 14 years, I found it an interesting read.

"A relational database contains tables that relate to each other by key values" I really do think this is a fair statement - If you have a database that contains tables that do not relate to each other it wouldn't be very relational would it and that is the point the article is making.

Good start, looking forward to the next article and be thankful you don't have to work with some of the people that leave comments!