I knew how important databases are for developers, but I always found it boring whenever I studied the theory in this field. Yongjun's lecture explained the core database theory concisely and clearly, allowing me to learn with interest. The explanations through real-world examples were a great help in understanding the theory intuitively! I'm also taking the SQLD exam soon, and I think this will be very helpful for exam preparation as well. Thank you for the great lecture.