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
About the Authors
About the Reviewers

Chapter 6. Querying

We have our data stored nicely in SimpleDB domains. Now we are going to learn the different ways to retrieve the stored data. Most of us are used to using Structured Query Language (SQL) for retrieving data from relational databases. SimpleDB uses a select syntax that is very similar to its counterpart in SQL for the queries. In this chapter, we will explore the query syntax provided by SimpleDB with a lot of samples and learn about:

  • The basic select syntax

  • Quoting values inside select expressions

  • Predicates in select expressions

  • Comparison operators

  • Set operations

  • Sorting

  • Counting the results from SimpleDB queries

  • Queries on multi-valued attributes

  • GetAttributes