Practice in building databases?

I'm beginning to experiment with database creation on my own. I have read a lot about database theory and think I have an understanding of the basics of databases (primary and foreign keys, normalization, etc.). What I'm looking for at this point is some guided exercises for putting this theory into practice in an actual database. The material I've found so far falls into the category of real-world projects that are too complicated for me to process at this point or single-concept exercises that are too simplistic to help me stretch my abilities.

I'm hoping that the subreddit can suggest some exercises that require synthesizing some basic database skills but don't involve dozens of tables or incredibly complicated relationships. Are there standard practice databases that would be useful for a smart but novice learner?