Linq Unleashed for C#

Paul Kimmel

800 East 96th Street, Indianapolis, Indiana 46240 USA

Linq Unleashed for C#

Copyright © 2009 by Pearson Education, Inc.

All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions. Nor is any liability assumed for damages resulting from the use of the information contained herein.

ISBN-13: 978-0-672-32983-8
ISBN-10: 0-672-32983-2

Library of Congress Cataloging-in-Publication Data

Kimmel, Paul.
   LINQ unleashed for C# / Paul Kimmel. — 1st ed.
          p.cm.
   ISBN 978-0-672-32983-8
   1. C# (Computer program language) 2. Microsoft LINQ. I. Title.
     QA76.73.C154K5635 2009
     005.13’3—dc22
                                                                    2008030703
Printed in the United States of America
First Printing August 2008

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Editor-in-Chief

Karen Gettman

Executive Editor

Neil Rowe

Development Editor

Mark Renfrow

Managing Editor

Kristy Hart

Project Editor

Betsy Harris

Copy Editor

Karen Annett

Indexers

Lisa Stumpf

Publishing Works

Proofreader

Linda Seifer

Technical Editor

Joe Kunk

Publishing Coordinator

Cindy Teeters

Cover Designer

Gary Adair

Compositor

Jake McFarland

Contents at a Glance

Table of Contents

Foreword

Data affects just about every aspect of our lives. Everything we do is analyzed, scrutinized, and delivered back to us in the form of coupons and other marketing materials. When you write an application, you can be sure that data in one form or another will be part of the solution. As software developers, the ease with which we can store, retrieve, and analyze data is crucial to our ability to develop compelling applications. Add to that the fact that data can come in a number of different shapes and formats, and it quickly comes to light that there is tremendous value in a consistent framework for accessing many types of data.

Several different data access approaches have been developed for Windows developers over the years. ADO and OLEDB and subsequently ADO.NET gave us universal access to relational databases. MSXML and ADO.NET made it possible to inspect and manipulate XML documents. Each of these technologies had their benefits and drawbacks, but one common thread ran through each of them: They failed to deliver data access capabilities in a way that felt natural to developers.

LINQ now makes data access a first-class programming concept in .NET, making it possible for developers to express queries in a way that makes sense to developers. What makes LINQ unique is that it enables programmers to create type-safe data access code complete with Intellisense support and compile time syntax checking.

Paul Kimmel has done an excellent job of presenting LINQ in a concise and complete manner. Not only has he made LINQ approachable, but he has also masterfully explained concepts such as Anonymous Types and Lambda Expressions that help make LINQ a reality. The sample code throughout the book demonstrates the application of the technology in a clear and meaningful way. This is a great “Saturday morning with a pot of coffee” kind of book. I hope you’ll dive in and get as much out of this book as I did.

Darryl Hogan
Architect Evangelist, Microsoft

About the Author

Paul Kimmel is a four-time Microsoft MVP, the author of over a dozen books on object-oriented programming and UML, including three books on Microsoft .NET, a columnist for codeguru.com, developer.com, informit.com, devsource.com, and devx.com, a cofounder of the Greater Lansing Area .NET Users Group (glugnet.org, East Lansing and Flint), a full-time software developer, and sometimes pilot. Paul still lives and works in the greater Lansing, Michigan, area (and hasn’t given up on the economy). After 15 years of independent consulting, Paul now works for EDS as an application architect.

Dedication

This book is dedicated to the men and women of the United States armed forces, especially those brave souls serving in conflict zones, away from hearth and kin. To all military police men and women—Lookout Firefly it’s Night-train! Mohawk, 38 out.

Acknowledgments

Sometimes I read other people’s acknowledgements but a long list of names is boring unless it’s your name. If the casual reader is reading this, then you are helping me thank the myriad of people that make a book like this possible. If you are one of the people listed, then know that your able assistance is greatly appreciated.

Thanks to Neil Rowe, my acquisitions editor; Curt Johnson, marketing manager at Pearson; and Joan Murray, editor, also at Pearson. I wrote slower but finishing a book is thrilling.

Thanks to Joe Kunk for not complaining about how much work technical editing is and actually testing the examples. Joe also does a lot of heavy lifting at Glugnet East Lansing and Flint (our .NET User Groups). Thanks to the rest of the glugnet board for covering for me in my absence: Vivek Joshi, Alireza Namvar, Eric Vogel, Jeff McWherter, Vijay Jagdale, Jason Harris, Aaron Lilywhite, and Rich Hamilton.

Thanks to Bart De Smet from Microsoft for assistance with the Active Directory IQueryable provider—LINQ to AD is cool. Thanks to Daryl Hogan for the foreword.

I’d also like to mention Brian Dawson, Brad Jones, Tyler Durden, Jackson Wayfare, Blizzard for War Craft and Rockstar games for GTA IV, my kids Alex and Noah, Dena and Joe Swanson (for wine and comic relief), Ed Swanson for cigars, and all of the great folks at Pearson behind the scenes that turn my six-fingered manuscript into a shiny new book.

We Want to Hear from You!

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You can email or write me directly to let me know what you did or didn’t like about this book—as well as what we can do to make our books stronger.

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                  Sams Publishing
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