SQL

SQL Pocket Guide (Pocket Reference (O'Reilly))
$14.99
I was looking for a small SQL command resource and this fit the bill perfectly. The O'Reily series has never failed to hit the mark as a first class reference source. This book is small and pocketable and has provided me with the support I was looking for. I highly recommend this small powerful reference book!

Head First SQL
$45.00
This book really taught me about Databases in general and how to use them effectively. I was really just looking for a book that would teach me how to query correctly, but I was pleasantly surprised that this book teaches first, second, and third normal forms and how to properly normalize your tables. It really does go in depth. The reason I gave it 4 instead of 5 stars was because she spent the whole time on MySQL and didn't mention the others at all. I work with OJDBC (Oracle) and I was burned with some of the differences in syntax.
Overall, this is an excellent book to read for a beginner or even someone who wants to learn how to normalize tables properly.

SQL in a Nutshell (In a Nutshell (O'Reilly))
$44.99
I am reviewing the third edition.

This book is intended as a reference, not an instructional text. It serves this purpose well with pages and pages of great examples. The book is not focused on databases and SQL from a specific vendor, but gives great data and comparisons of commands and queries using ANSI SQL and then adjusting as needed for MySQL, Oracle, PostgreSQL, and SQL Server. If you are responsible for moving data from one vendor's product to another, or if you are responsible for databases from multiple vendors, this book could be a Godsend. Really, if you only use one of these products, the book is still a great value.

Keep in mind, this is not an instruction manual. This is a compilation of commands with examples. The goal is not to lead gently, but to get directly to the meat of using SQL, to give clear and detailed information about each command, its syntax and options, and several examples of usage. If that is what you are looking for, and especially a book with comparisons across platforms, this book will serve you very well.

Sams Teach Yourself SQL in 10 Minutes (3rd Edition)
$19.99
I wouldn't say it quite teaches SQL in 10 minutes, but it is just what I wanted. Excellent examples and very concise--makes it very easy to pick up a lot of commands very quickly.