I wouldn't treat this sort of thing as dispositive, and if I were doing hard-core SQL development, I'd dismiss it entirely and start the interview with much hairier wizardry; but for a generic, gonna write some queries but mostly live outside the database kind of role, the five minutes or so this sort of test takes at the beginning of the interview gives me a strong indicator of how to assess what the candidate actually knows, rather than what is represented on their resume. It is a guide for the actual meat of the interview.