I skipped the JPA basics and went straight to using it. I was confused at the beginning of the entity design, but I was able to finish it safely. The criteria part in the dynamic query generation is really hard to read and has a lot of unfamiliar words, so it seems difficult to use it without the help of IntelliJ @_@. It would have been nice if it could be used intuitively like LINQ in C#.. Still, QueryDSL seems more human(?), so I feel reassured. I will run hard until QueryDSL! I have to go to the basics first, though ㅋㅋ