Some of the most unused yet powerful functions in T-SQL are Window functions. These functions are powerful because they allow calculations on a Window of the data you specify, even while the calculation scrolls through your data.
Hmmm…. What to use… What to use? When I want to explore data quickly and with the least amount of pain, the first problem I face is where do I start. There are a million approaches and I’m usually thinking long-term, ease of maintenance, surrounding platform, etc etc.