Nice and simple.

I'm very surprised there's only 34% correct so far, although I would expect the wiggle on whether no other user is connected to a db which is in single-user mode would catch a few who didn't think hard (it returns 1 if an attempt to connect would have succeeded, which makes it pretty obvous that it can't return 1 if someone else is connected in single user mode, but while Vulcans might always get something like that right us poor humans sometimes don't think hard enough), but that doesn't seem to account for enough of the wrong answers.