A step-by-step SQLAlchemy tutorial

SQLAlchemy is a very useful database-access library for Python. It’s got excellent documentation; but what it was missing until recently was a tutorial. I wrote a step-by-step SQLAlchemy tutorial to fill in the gap. Of course, the day after I wrote it, SQLAlchemy’s author posted the tutorial that he’d been working on, so I just duplicated his efforts. :-)

Nevertheless, it might be useful to someone, so I put it up anyway.