Yesterday's practice! I just finished the course on Spring Boot and JPA Utilization 2 - API Development and Performance Optimization. Time flew by. I have been teaching IT-related technology for 20 years, but I am amazed by the level of lectures and the skills of instructor Kim Young-han. Yesterday, I was seriously immersed in John Wick 4, which I usually like, and enjoyed it. This was 10 times more fun than John Wick 4. In 2004, I was the first to teach Hibernate in Korea, but no one in the field used it, so I stopped teaching for a while. However, it seems like only yesterday that instructor Kim Young-han was asking me to teach Hibernate when he was attending our academy in 2006, and he was recognized for his outstanding skills at Baedal Minjok, and while working, he quickly grew from team leader to the youngest CTO in Korea, and now he is starting a new challenge to nurture the next generation, so I want to send him endless support. I had a brief conversation with Mr. Kim Young-han, the best disciple of 21 years at Seoul IT Education Center, yesterday about the lecture content related to JPA extreme tuning, and I learned a lot from him because he is a true scholar. The content that emphasizes that the entity corresponding to the model layer should be designed independently of the screen or API used by a specific VIEW using DTO, and the detailed explanation and solution method of instructor Kim Young-han on tuning to wisely solve 1-to-many problems, and the sincere lecture that shows each SQL statement created by JPA in detail and does not just skip over each important line of code are amazing. I send endless support to instructor Kim Young-han's new challenge history. Fighting^^