I haven’t tried this yet, but it looks really cool. It’s basically an almost-SQL92 complete implementation of a database engine without a separate database process required — the databases are stored on disk as files. I’m hazarding a guess that this sprung from the limitations of Berkeley DB as a scalable, lightweight file-based database implementation.
Surprisingly the missing features list (that stop it short of full SQL92 compliance) is fairly short, which implies to me that even transactions are supported.
Seems like a great tool for small jobs where a full-blown PostgreSQL or MySQL database is just overkill.