Скачать или смотреть SQL Window Functions - Rolling/Sliding/Moving Totals

I spent FOR EVER trying to figure out how to do a simple "rolling total", or "sliding total" in SQL. But with window functions, it turns out that this is easy. All it takes is one line of code. And I wanted to share that with you.

When I use the term "rolling" or "sliding" total, I'm referring to a sum that looks back across a certain range of time. For example, if you have daily sales data for the period of a whole calendar year, you might want to know the sum of the previous 14 days of sales for each day in that year. This is similar to a moving average, but perhaps a "moving total" would be a more accurate description. Anyway, that's what this video is about.

0:00 -- Introduction
0:19 -- Explanation begins
2:14 -- Walkthrough tutorial
3:34 -- Introducing the Window Function
9:13 -- Recap