Hello! In the previous part, we showed you a very complicated query that might have looked a bit scary to you. In this part, we're going to start from the very beginning. Step by step, you will learn new elements that make up window functions. We hope that at the end of our course, you will take one more look at that scary example and think: this is now so easy!
But first things first. We'll start with introducing today's tables. We're going to deal with employees, their departments and purchases in each department. Not very original, you can find such tables in many database examples, but that's exactly the point – we want you to feel comfortable when you take your first steps with window functions.