It seems as though interviews require a lot of preparation for knowledge that won't be used for the actual job. It's discouraging because I'm the type to forget things when I don't use the knowledge in my every day work.
As an application developer interviewer I've been burned by people that are "book smart". They tend to rely on what they learned or remember, but cannot solve problems as that skill isn't taught in a book. My interviewing questioning has now shifted to what projects that person has worked on and what experiences they went through during the project. The answers I get provide me with enough information about the person and how they go about solving issues they encounter. So, my advice is don't get discouraged and just be honest about your experiences and what you know from memory. I wouldn't hold it against anyone that they use a search engine to look up syntax. :) Doctors do the same thing when they run into problems they are unfamiliar with.