LINQ Unleashed: for C#

by Paul Kimmel

Overview

Foreword by Darryl Hogan, Architect Evangelist, Microsoft Corporation

 

Microsoft’s highly anticipated LINQ query technology makes it easy to retrieve any information programmatically from any data source, no matter where it comes from or how it’s stored. Using LINQ, developers can query objects, relational databases, XML documents, and ADO.NET datasets--and do it all directly from C# 3.0, leveraging the powerful capabilities of LINQ.

 

This is a definitive guide to getting real-world results with LINQ, using C# 3.0 and Visual Studio 2008. In LINQ Unleashed, Microsoft MVP Paul Kimmel covers every facet of LINQ programming, showing how LINQ can help you dramatically improve your productivity and build more reliable, maintainable applications.

 

Kimmel begins by reviewing the state-of-the-art C# programming techniques LINQ uses, including anonymous types, partial methods, and Lambda expressions. Next, using realistic examples and easy-to-adapt sample code, he details the most powerful new LINQ techniques for accessing objects, databases, and XML. You’ll gain a deep and practical understanding of how LINQ works “under the hood”--and learn how to do everything from selecting data through integrating XML with other data models.

 

• Build efficient LINQ queries to .NET objects, SQL databases, and XML content
• Utilize anonymous types to reduce design time, coding effort, and debugging time
• Automatically generate .NET state machines with the new yield return construct
• Master LINQ query syntax, operators, extension methods, sorting, grouping, aggregate and set operations, and more
• Make the most of select--and use it in the business layer of your n-tier applications
• Query relational data stored in Microsoft SQL Server
• Use nullable types to eliminate unnecessary database access plumbing code
• Use LINQ with ADO.NET 3.0 and Microsoft’s powerful new Entity Framework
• Extract XML data without the hassles or complexity of XPath
• Automatically construct XML from CSV files and other non-XML data
• Query Active Directory by extending LINQ

Product Details

ISBN-13:	9780768685374
Publisher:	Pearson Education
Publication date:	08/19/2008
Series:	Unleashed
Sold by:	Barnes & Noble
Format:	eBook
Pages:	552
File size:	4 MB

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.

Table of Contents

Introduction  1

Part I     Getting Ready for LINQ

       1     Programming with Anonymous Types 5

       2     Using Compound Type Initialization  29

       3     Defining Extension and Partial Methods  61

       4     yield return: Using .NET’s State Machine Generator  85

       5     Understanding Lambda Expressions and Closures  97

       6     Using Standard Query Operators  121

Part II    LINQ for Objects

       7     Sorting and Grouping Queries 137

       8     Using Aggregate Operations 151

       9     Performing Set Operations  167

       10   Mastering Select and SelectMany  185

       11   Joining Query Results  211

       12   Querying Outlook and Active Directory  239

Part III   LINQ for Data

       13   Querying Relational Data with LINQ 265

       14   Creating Better Entities and Mapping Inheritance and Aggregation  289

       15   Joining Database Tables with LINQ Queries  309

       16   Updating Anonymous Relational Data  349

       17   Introducing ADO.NET 3.0 and the Entity Framework  383

Part IV  LINQ for XML

       18   Extracting Data from XML 415

       19   Comparing LINQ to XML with Other XML Technologies  437

       20   Constructing XML from Non-XML Data  453

       21   Emitting XML with the XmlWriter  463

       22   Combining XML with Other Data Models  469

       23   LINQ to XSD Supports Typed XML Programming  485

Index

Preface

Introduction

By the time you are holding this book in your hands, I will have 30 years in since the first time I wrote some code. That code was ROM-BASIC on a TRS-80 in Washington grammar school in Owosso, Michigan, and I was in the fifth grade. Making the "tank" slide back and forth shooting blips across the screen was neat. Changing the code to change blip speeds and numbers of targets was exhilarating. Three decades later and I get more excited each passing year. There are great technologies on the horizon like Microsoft Surface, Popfly, and LINQ. This book is about LINQ, or Language INtegrated Query.

LINQ is a SQL-like language for C#. When I first saw it, I didn't like it. My first impression was that someone had glommed on a bastardization of C# and it was ugly like SQL can get. I didn't like it because I didn't understand it. However, I gave LINQ a second chance (as I want you to do) and discovered that LINQ is thoroughly integrated, tremendously powerful, and almost as much fun as a Tesla Roadster or doing hammerheads in an Extra 300L.

The query capabilities of LINQ are extended to objects, SQL, DataSets, XML, XSD, entities, and can be extended to other providers like Active Directory or SharePoint. This means that you can write queries—that are similar in syntax—against objects, data, XML, XSD, entities, or Active Directory (with a little work) much like you would a SQL query in a database. And, LINQ is actually engineered artfully and brilliantly on top of generics as well as some new features in .NET 3.5, such as extension methods, anonymous types, and Lambda Expressions. Another very important characteristic of LINQ is that it clearly demonstrates Microsoft's willingness to innovate and take the best of existing technologies like Lambda Calculus—invented in the 1930s—and if it's good or great, incorporate these elements into the tools and languages we love.

LINQ and its underpinnings are powerful and challenging, and in this book you will get what you need to know to completely understand all that makes LINQ work and begin using it immediately. You will learn about anonymous methods, extension methods, Lambda Expressions, state machines, how generics and the CodeDOM play a big role in powerful tools like LINQ, and writing LINQ queries and why you will want to do it in the bigger, grander scheme of things. You will also learn how to save a ton of time and effort by not hard-coding those elements that you will no longer need or want to hard-code, and you will have a better grasp of how LINQ fits into n-tier architectures without breaking guidelines that have helped you succeed to date.

Brought to you by a four-time Microsoft MVP and columnist for over a decade, LINQ Unleashed for C# will teach you everything you need to know about LINQ and .NET 3.5 features and how to be more productive and have more fun than ever before.

Conventions Used in This Book

The following typographic conventions are used in this book:

Code lines, commands, statements, variables, and text you see onscreen appear in a monospace typeface.

Occasionally in listings bold is used to draw attention to the snippet of code being discussed.

Placeholders in syntax descriptions appear in an italic monospace typeface. You replace the placeholder with the actual filename, parameter, or whatever element it represents.

Italics highlight technical terms when they're being defined.

A code-continuation icon is used before a line of code that is really a continuation of the preceding line. Sometimes a line of code is too long to fit as a single line on the page. If you see before a line of code, remember that it's part of the line immediately above it.

The book also contains Notes, Tips, and Cautions to help you spot important or useful information more quickly.

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