The instructor's lectures are great because they make a lot of content easy to understand, and above all, I feel that the biggest strength is that they don't easily skip over 'Why? How come?' Even if you know how to use a tool, if you don't understand the principles or reasons behind it, you might end up using it in the wrong place or in the wrong way, even if you follow the usage correctly. I think this design lecture was particularly well-suited to the style that emphasizes 'Why? How come?' because it had recommended methods and their comparison groups, like identifying-non-identifying and natural keys-surrogate keys. Thank you for your hard work.