I've been lucky in that I haven't had to be the interviewee in a while, bit I've been the interviewer quite a bit.

My first piece if advice (which is pretty well-known, so I apologize if I'm being obvious): know a bit about the company you're interviewing with. Since researching the company is pretty easy to do, there's no real excuse for you to walk in and not know what the company does, their mission statement, etc. So, if you can ask a few questions or make a few observations about how your skill set can support that mission, you're positioning yourself as an attractive candidate. Since you're a SQL guy, you should try to figure out what data sets they're working with and what challenges that data would bring.

I also agree with Nick: if the company picks up on your bitterness, that would make you less attractive.

As for what skill sets to brush up on, you'd have to glean that from the job description. For example, if it mentions replication and that's one of your weaker areas, you'd definitely want to brush up on that. But don't try to whitewash where you lack experience; a lot of interviewers have pretty well developed BS detectors. When I'm interviewing, I give candidates points for admitting they haven't done a lot of hands-on with a particular technology but can demonstrate that they are familiar with the basics and are willing to learn more. If they claim to be expert at it, I'm likely to ask some pretty deep dive questions which, if they can't answer, they'll have lost a lot of credibility.