I believe what Mohit C meant was if you are going to use those DB you're not in for a treat. I'm trying to brush up for an interview, and alot of the questions are more confusing than anything else, and some contradicting others.
I do appreciate the effort that they put into those sites, but alot of the questions are dumb as hell. What they really need is a comment/discussion system to accompany the questions.
To make my point, look at Flight Planning, questions 1 and 6. Phrasing ridiculous, and answers inaccurate (or maybe i'm just more rusty than I thought I was ; ))