https://cs50.harvard.edu/sql/2023/
https://mystery.knightlab.com/
https://news.ycombinator.com/item?id=35665142 + https://news.ycombinator.com/item?id=31355809 +
https://lost-at-sql.therobinlord.com/
https://news.ycombinator.com/item?id=35247242 – mysql for developers e-learning
https://gvwilson.github.io/sql-tutorial
https://www.databasestar.com/sql-roadmap + https://www.databasestar.com/vip