asql, or ASql, is a platform independent, extremely lightweight, and a free software C and Python library that provides a self-contained, serverless, zero-configuration, transactional SQL database engine.
ASql does not implements any SQL standard, but instead of that has pure C and Python interface "simulating" SQL queries that brings full power of database programming, including database transactions that are atomic, isolated, and durable.
Official Site: http://code.google.com/p/asql/