T-SQL Querying is a very good overview of SQL Server queries, indexing, best practices, optimization and troubleshooting. I can't imagine someone can just read it and be done with it, as it is full of useful references, so it's good to keep it on the table. Also, it's relatively short, so one can peruse it in a day and then keep using it while doing SQL work.
What I didn't like so much was the inconsistent level of knowledge needed for the various chapters. It starts with a tedious explanations of types of queries and what JOINs are and what ORDER BY is and so on, then moves on to the actual interesting stuff. Also, what the hell is that title and cover? :) You'd think it's a gardening book.
Another great thing about it is that it is available free online, from its publishers: Packt.