prophet001

It's a bad-faith trick question of little-to-no utility in assessing an applicant's capability, as outlined elsewhere ITT. The principle being asked about, in addition to being obscured by the wrong terminology, is a bad database design principle anyway, as also outlined elsewhere ITT.

You're correct in your assessment that the use of the word "recursive" isn't even technically applicable here. OP thinks they have come up with a good way of assessing an applicant's critical thinking skills, when all they've done is managed to show the world that they're contributing to the tech industry hiring struggle with their overweening view of their own understanding of both technology and human behavior.

How often do you hear the right answer? (I.e. "that's poor relationship design, don't do it?")

So I've had to maintain multiple schemas designed by people who thought this, and it's always more difficult to maintain and expand than creating a linking table in the first place would have been.

It's mathematically elegant, in practice it's just a major pain in the ass.

And you shouldn't, because it's piss-poor design due to its utter lack of maintainability.

You mean a junction, or linking table? Pivot tables aren't really a thing in RDBMS schema design, if a pivoted representation is required, that's what a view containing one or more PIVOTs/UNPIVOTs is for.

Recursive FKs are a maintenance nightmare, and are the very definition of painting yourself into a corner. Linking tables for 1-1 relationships are of course silly, unless that relationship is between two records in the same table, but they have nothing to do with pivoting a projection.

NGL dude, you're kinda making it sound like you're not qualified to be interviewing engineers.