Book Image

Amazon SimpleDB Developer Guide

Book Image

Amazon SimpleDB Developer Guide

Overview of this book

SimpleDB is a highly scalable, simple-to-use, and inexpensive database in the cloud from Amazon Web Services. But in order to use SimpleDB, you really have to change your mindset. This isn't a traditional relational database; in fact it's not relational at all. For developers who have experience working with relational databases, this may lead to misconceptions as to how SimpleDB works.This practical book aims to address your preconceptions on how SimpleDB will work for you. You will be quickly led through the differences between relational databases and SimpleDB, and the implications of using SimpleDB. Throughout this book, there is an emphasis on demonstrating key concepts with practical examples for Java, PHP, and Python developers.You will be introduced to this massively scalable schema-less key-value data store: what it is, how it works, and why it is such a game-changer. You will then explore the basic functionality offered by SimpleDB including querying, code samples, and a lot more. This book will help you deploy services outside the Amazon cloud and access them from any web host.You will see how SimpleDB gives you the freedom to focus on application development. As you work through this book you will be able to optimize the performance of your applications using parallel operations, caching with memcache, asynchronous operations, and more.
Table of Contents (16 chapters)
Amazon SimpleDB Developer Guide
Credits
Foreword
About the Authors
About the Reviewers
Preface

Combining expressions


Multiple select expressions can be combined using: INTERSECTION, OR, AND, NOT, and parentheses ( ).

<select expression> intersection <select expression>
NOT <select expression>
(<select expression>)
<select expression> or <select expression>
<select expression> and <select expression>

SimpleDB supports both the set operators—INTERSECTION and UNION. The INTERSECTION operator can be used to retrieve items matching the specified predicates on both sides of the operator. The UNION operator is used for retrieving items that match either of the specified predicates. The UNION operator works only with the old query syntax and will not work with the new Select syntax. You should use the OR operator instead of UNION.

INTERSECTION

Retrieve all songs that are released after 1980 and are in the Rock genre:

SELECT * FROM songs WHERE Year > '1980' INTERSECTION Genre = 'Rock'

SELECT * FROM songs WHERE Year > '1980' returns:

Item...