Wikipedia says that “Relational calculus is essentially equivalent to first-order logic, and indeed, Codd’s Theorem had been known to logicians since the late 1940s.”  I couldn’t find the cited sources online, but did find these interesting papers:

“Applications of Alfred Tarski’s Ideas in Database Theory”

and

“Tarski’s influence on computer science.” (see the section starting “The final thing I want to tell something about is the connection of Tarski’s ideas and work with database theory.”)

If you’ve studied mathematical logic (or math, eg, topology), you are probably familiar with Tarski’s name.  The historical …

As most people still do I learned to read using books. WhooHoo!

Books are nice. Besides reading them they are also a nice decoration on your shelf. There is a brilliant TED talk by Chip Kidd on this subject.

But sometimes books have drawbacks. This is where I have to start the comparison with vinyl records (Yes, you're still reading a database oriented blog). Vinyl records look nice and are still being sold and yes I also still use them. The drawback is that car dealers start to look puzzeled if you ask them if your new multimedia system in your car is able to play your old Led Zeppelin records. The market for portable record players is small, and that's for a good reason.

The problem with books about databases is that they get old very soon. …

It seems that a lot of people equate non-SQL databases with non-relational-ness, or malign the word relational. This is pretty much pure ignorance. If you’ve ever uttered a sentence that includes the phrase “…non-relational database…” then I have two suggestions for you.

1. Study relational algebra. At a bare minimum, read the Wikipedia article on relational algebra. There is much more you could do — take a class on the topic, or read C.J. Date’s SQL and Relational Theory (my review). Ask yourself how similar SQL is to the relational algebra. How is relational algebra different …