I like questions related to covering indexes, and I always have that card in the interview deck, because answering this question involves practical knowledge, especially if the interviewer asks a followup question like: "So, how do you know that a query is actually covered by an index?". Many candidates applying for an application development job may consider intermediate level questions about things like covering indexes to be "tricky". However, if the candidate would actually be coding SQL or modeling tables and indexes as part of their job, then it's not a trick question.
I fully agree with Eric.
:-PManie Verster
Developer
Johannesburg
South Africa
I can do all things through Christ who strengthens me. - Holy Bible
I am a man of fixed and unbending principles, the first of which is to be flexible at all times. - Everett Mckinley Dirkson (Well, I am trying. - Manie Verster)