SQL Window Functions and CTEs

You can do quite a lot with some of the most popular SQL queries such as SELECT, WHERE, and JOIN. But there exists some question that you cannot answer with these queries such as What is each student's mark compared to their own average?" or "Can we rank results without losing any rows?" That is where window functions and CTEs come in. They sound intimidating, but once they click, you will wonder how you ever wrote SQL without them. Part 1 - Window Functions What even is a "window"? Think about