Ask HN: Are there any websites for SQL puzzle games?

As a Python programmer, I often use Django or SQLAlchemy ORM and as a consequence, my proficiency in raw SQL remains at a basic level. However, I am keen on improving my raw SQL skills, given it's sometimes superior to ORM, and because I find SQL and relational algebra surprisingly fun to think about.

Does anyone know of websites that provide SQL puzzle games that allow users to solve problems by writing SQL and validating them? I believe this would be an engaging way to enhance my SQL skills. Your suggestions are appreciated!