The [amazon_link id="1449394094" target="_blank" ]SQL Pocket Guide (3rd edition)[/amazon_link] by Jonathan Gennick (O’Reilly, 2010) is a must have for the database butterfly. I move among several DBMS on an almost daily basis. Once in a while I need a refresh on how one flavor of SQL differs from another. In comes the Pocket Guide. The Guide covers the latest versions of DB2, MySQL, Oracle, PostgreSQL, and Microsoft SQL Server. Gennick points out where commands and syntax vary from one platform to another and which commands are unique to certain platforms or versions. Examples of where these differences are tricky and where this book comes in handy are in areas like date/time and number conversion. This Guide is a short, abbreviated reference text which doesn’t pretend to be a comprehensive reference. For comprehensive you will definitely want the [amazon_link id="0596518846" target="_blank" ]SQL in a Nutshell (In a Nutshell (O’Reilly))[/amazon_link].
While great for quick reference it is not intended to be a textbook. It can certainly be used as a refresher and has nice, short explanations of each command together with the examples. To find commands you will really want to already have an idea of what you are looking for and will need the table of contents and the index. If you are using an ebook format the search capability makes it an even handier reference text.
Disclaimer: I was provided a copy of this text by the publisher for review.