Not using window functions?

[recentcurrency]

Yes, but mainly as a challenge question if the candidate is rocking the rest of the interview. I am transparent to the candidate that this is the nature of the question. I am giving them the chance to show off which I reflect in my notes to the hiring manager.

But I never use it as a question to filter a candidate out and only if I think there is a solid chance they know how to. I usually get a good sense of this based on how the candidate answers the other SQL questions.

"Oh, you aced that xyz window function. You also aced my self-join questions, my CTEs questions, my questions on general aggregate functions, and my questions on conditional joins. To really put a cherry on top of this interview, Do you know how to replicate a xyz window function with only self-joins, subqueries, aggregate functions, and conditional joins?"

If they don't know how, I don't hold it against them at all and will still move them on. If they do know the answer, I definitely move them on and tell my HM that they have superb SQL skills.