This book belongs in the pocket of every mySQL programmer who doesn't yet have it memorised.
While this is a relatively small book (will fit in your pocket), I can't help but feel that the book could have been reorganised in a way that would have made it a lot smaller still.
The book provides a separate section that outlines the regular expression syntax supported by each of the many different languages that the book covers. While this information is thorough in scope and laid out in meaningful tables, the fact that large sections of the information are the same for each of the languages makes the book very repetitive. The provided format both makes large sections of the book redundant (those languages you are not using) and also makes it difficult to tell if switching to an alternative language would provide the options that you need to more easily perform your desired task.
I would have preferred to have all of the information listed once with each option then indicating which of the languages do/do not support that option. This would have made the book less than half the size, would have made it less repetitive, and would have provided better information on alternative languages that might be preferable to use for specific commands.