Start with SQL using this video: https://www.youtube.com/watch?v=HXV3zeQKqGY&t=2611s
Then PostgreSQL: https://www.youtube.com/watch?v=qw--VYLpxG4
And for using it in production, here's Supabase and a tutorial to get started with PostgreSQL: https://www.youtube.com/watch?v=dU7GwCOgvNY
That's 10 hours of video, and thanks to that, as a beginner, I managed to create a database for a site with 10,000 users per month. Good luck!