Why This Book?
The primary source of information for relational databases is the
documentation and help files provided by the vendors themselves.
While each vendor's documentation is an
indispensable resource that most database programmers and database
administrators turn to first, it has a number of limitations:
It covers only a single, specific vendor's product.
There is no coverage for translation, migration, or integration
It describes programming methods, usually in a multitude of small,
disconnected documents or help files.
It covers individual commands, often in confusing detail, obscuring
the simple and direct uses of commands that are used every day by
programmers and administrators.
In other words, the documentation included with the vendor database
is an exhaustive explanation of every aspect of their platform. After
all, help texts are naturally geared toward delivering the main facts
about the product. They'll tell you a
command's specific syntax (and all its obscure
variants) and, in general terms, how to implement it. However, if you
move between RDMS's and you need to be productive
very quickly, you will rarely use those obscure command variations
and instead utilize the common capabilities in real-life situations.
This book begins where the vendor documentation ends by distilling
the experiences of professional database administrators and
developers who have used these SQL variants day in and day out to
support complex enterprise applications. You'll get
the benefit of their experience in a compact and easily usable
format. Whether SQL is new to you or you have been using SQL since
its earliest days, there are always new tips and techniques to learn.
And, when moving between different implementations,
it's always important to find out about the
implementations that can bite you if you're not
careful and informed.