I'm working on a project for my portfolio to prepare for employment, and I always thought about improving performance, but I had no idea how to do it or how to tune queries. When I looked at the book, it was mostly theoretical content, so I was worried and bought the lecture to watch it. First of all, people said that they improved by creating indexes, but I didn't know what criteria they had to use to create the indexes, but after watching this lecture, I found out! And I knew about the explain command, but I didn't know how to view it or how to interpret it. I learned it clearly through this lecture, and I plan to apply it to query tuning for future projects. Thank you!!