I was short on time, so I studied DB superficially, and when I first listened to it, I only acquired the knowledge necessary for basic projects, so I thought, "Conceptually, it's difficult." I felt sorry to just throw away this great lecture, so after finishing the project and studying DB, I listened to it again and I think it's a really great lecture. I'm writing this with a happy heart because I thought I'd leave a review if I understood it properly. It may not be the right expression, but I really enjoyed it.