Public SQL database for educational purposes

Question

I am looking for a publicly available SQL database with free access, where one can run some SELECT queries for free on some meaningful data (not item1, item2, item3

Answer 1

I like the concept of a game on pure SQL as implemented here: https://mystery.knightlab.com
It offers gamification of learning SQL and includes an optional tutorial-like introduction.
If you already know SQL but feel a little rusty, then this is fun to brush up.
For beginners it is an easy hand-help first contact.

The data are artificial and have a slightly steep drop-off when leaving the immediate game track, but I think it still matchs your requirement to be "meaningful". (And if you go intentionally off-track, then there are hints that some easter-eggs can be found, in the shape of jokes. I did not yet manage to get the query right to actually read them... So I think that even beyond the obvious game there is something for the more experienced to hunt for.)