SQL Pocket Guide by Jonathan Gennick is book that addresses SQL across multiple platforms. The Book tries to talk about SQL syntax across the major databases, which include Oracle 11Gr2, DB2 9.7, Postgres SQL and SQL Server. Not All SQL is standard and variations of SQL in terms of Syntax are clearly highlighted and explained. The Book is written by Jonathan Gennick whose previous titles include SQL* Plus a definitive guide, Books on SQL Loader & regular expressions.
The SQL Pocket Guide is not a guide that is meant for cover-to-cover reading. This Book is rather a keep for the times when you need to find examples for SQL. Since my work with SQL has been for Oracle based Databases. I was intrigued by how SQL compares between Database vendors. E.g., CAST function was explained and pros and cons explained were brought to light that SQL Server has a better function called CONVERT that does a better job than CASE.
In This Age of Google searches and trying to find solutions in form of a web search, I feel Books Like these still play their part and should be in the arsenal of every Database Professional. While I did not read the entire book, the sections I scanned thru and the statements I used were definitely well explained and examples were of good value. The Book provides and easy reference with good online examples that can be downloaded and used to test syntax.
Further Book Details can be found here.