SQL Paul (11/16/2011)
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.
I agree about theVenn diagrams, they will be a great aid to people who don't have a gut feel (as opposed to a theoretical idea) for what the operators concerned do, and the gut feel is probably more important than the theory. And the whole article is certainly interesting. My concern with it was that it was a bit sloppy on mathematical terminology for an article with that title.
"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.
I think it's a fair statement too - it's a nice way of saying that referential transparency enforced by keys is an essential part of the relational model, which will be useful for people coming to the subject from no background of relational theory or terminology. I think DP was the only person to object to the statement.
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!
I hope the next article comes soon.
Tom