Well, having avoided it for as long as possible, preferring to use the Jena API, I now find myself having to know how to form RDQL queries. RDQL is an implementation of an SQL-like query language for RDF., and it’s also not actually that easy, especially if you’ve heard people say things like “It’s just SQL for RDF!” (which it may be in theory but in practice is completely different – RDQL has almost an arcane quality to it, appearing to the casual eye as akin to alchemists’ symbols, but I digress).

Some of the tutorials I’ve dug out:

• A Programmer’s Introduction to RDQL (I also found an older version of this on the HP site)
• RDQL Tutorial

and it’s worth comparing two slides which perform the same query, one in RDQL and one on SQL.

There are also four public data repositories you can try your newly-learned skills on (including a museum repository and a a vCard repository).