First, from someone with 25 years of SQL development experience, let me say while it may be true these skills could be learned in a week, most are not learned at all even by regular practitioners.

And as with all such questions I'm judging your comfort with the concepts behind the skills - in this case set theory, conditional logic, data modeling, etc.

So it's more how you say it, not what you say it. And yes it's mostly negative signal - most interviews are just to weed out completely hopeless candidates.

> Why would you ask interview questions to quiz on skills that can be learned in a week?

I'm not an SQL expert, but it's very important to understand whether something is a known unknown or unknown unknown to a candidate. So, I imagine, if the candidate would say something along the lines of "oh, this looks like something for a window function - I don't know the syntax and the nitpicks, but I could google it", it'd be completely OK. However, if he wasn't even aware that such a tool existed, it means that he would never go and learn it in a week without outside guidance, and would choose a less-fitting tool to complete a task.

One thing I mention in the doc intro is that SQL questions are one part of the data analyst interview, not all of it. If this doc helps people get through the SQL questions so that they can spend more time being thoughtful with open-ended analytics questions, that's good thing (both for interviews and for work more generally)!