It does not have any functionality to test databases other than indirectly through web applications and HTML pages.
"Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well."
One option to test database information is to use a programming framework for Selenium that allows access to application database information, usually through an implementation of ORM (Object-relational mapping). One example is ruby-on-rails with RSpec which could allow you to both check the web page view using the Capybara DSL and also check database information via Active Record. Be aware however that there are asynchronus and timing issues here. Recently we stopped doing the database check due to these issues which were causing the dreaded intermittent test failures.
[Update - baed on your links the old selenium 1.0 'RC' version had a way but this is now being phased out and is un-supported.