It was tough!! In practice, I used Spring JPA without much understanding and just thought of it as a convenient technology that doesn't require writing queries, but I learned a lot after listening to the lecture. I listened to the lecture while thinking about problems and solutions while unfolding the DB ERD of the current project, and it was a great help. I need to start over from the entity design stage, but I am grateful that I can learn about it and fix it now. Thank you again for the great lecture.