It was a great lecture that helped me correct the concepts I had vaguely and inaccurately about transactions. I started by writing @Transactional in the service layer without thinking and without knowing the reason, but now I know what it means and I'm so happy to be able to use it. And during the lecture, I encountered a problem with a call inside a transaction in real practice, and the lecture content came to mind so magically that I was able to solve it in 5 minutes. Thank you for the lecture.