One project is worth highlighting here, as it is a good indicator of my competence in relational database design.
Universal Classical Music Database
Written in 2005, this database design is an exercise in perfectionism, to properly map the structure of the classical music world to a relational database. The size of the resulting structure is irrelevant and impractical for implementation by a single developer.
Nevertheless this is a particularly carefully crafted design, and was helped by my strong domain knowledge in classical music.