I was just guessing that there must be a reason and this is the function, and I was using Spring, but I had some free time before starting the project, so I'm clearing the lectures that I bought a long time ago and haven't seen. Originally, I was a scholar (I bought a lot of books and looked them up), but as I worked, I became a forced wild type. Compared to the past, I can fix errors faster and I don't have any problems making money, but it's harder to analyze thoroughly separated code than long and unorganized code, so I thought something was wrong. So I started watching from the basics, and I found out that the codes that were difficult to analyze were codes that were automatically injected. I also feel relieved that I learned the principles of annotations that I used to use without thinking. First, I cleared all the lectures that I bought, and I put the JPA lectures in my shopping cart to buy. The build-up explanation method is really good, and the voice is exciting, so it's not boring. When I'm busy worrying about naming, it's annoying I think I'll use the shortcut key Ctrl+alt+v very preciously, and I've never used shortcut keys like Ctrl+E and F2 but I think I'll use them very usefully. If I get a request to recommend a lecture related to Spring, I'll definitely recommend it. Thank you.