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LINQ Quickly
A practical guide to programming Language
Integrated Query with C#
N Satheesh Kumar
BIRMINGHAM - MUMBAI
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LINQ Quickly
Copyright © 2007 Packt Publishing
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However, Packt Publishing cannot guarantee the accuracy of this information.
First published: November 2007
Production Reference: 1161107
Published by Packt Publishing Ltd.
32 Lincoln Road
Olton
Birmingham, B27 6PA, UK.
ISBN 978-1-847192-54-7
www.packtpub.com
Cover Image by Vinayak Chittar ([email protected])
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Credits
Author Project Manager
N Satheesh Kumar Abhijeet Deobhakta
Reviewer Project Coordinator
Granville Barnett Patricia Weir
Senior Acquisition Editor Indexer
Douglas Paterson Hemangini Bari
Development Editor Proofreader
Nikhil Bangera Cathy Cumberlidge
Technical Editor Production Coordinators
Sarvesh Shanbhag Aparna Bhagat
Shantanu Zagade
Editorial Manager
Dipali Chittar Cover Designer
Aparna Bhagat
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About the Author
N Satheesh Kumar has a Bachelor's Degree in Computer Science Engineering and
has around eleven years of experience in software development lifecycle, project and
program management. He started his career developing software applications using
Borland software products in a company based in India, and then moved to the
United Arab Emirates where he continued developing custom application software
using Borland Delphi, and customizing Great Plain Dynamics (now known as
Microsoft Dynamics) for an automobile company. He moved back to India and spent
three years in design and developing application software using Microsoft products
for a top multi national company, and then spent a couple of years in project
management and program management activities. Now he works as a Technical
Architect for a top retail company based in the United States. He works with the
latest Microsoft technologies and has published many articles on LINQ and other
features of .NET.
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About the Reviewer
Granville Barnett's interest in programming has spanned many languages; his
talents have been applied most notably at Microsoft. Granville has worked with
LINQ since the LINQ May 2006 CTP and has since then advised some of the biggest
companies in the world on the successful application of LINQ. Granville has a very
active interest in data structures and algorithms, and compiler theory, design and
implementation.
He would like to thank all at Microsoft, in particular the members of the UK
Application Development Consulting team.
As an author, Granville has written several magazine and web articles on LINQ.
He can be reached through his website at http://gbarnett.org.
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Table of Contents
Preface 1
Chapter 1: Overview 5
LINQ Architecture 5
Integration with SQL 7
Integration with XML 7
Support for C# 3.0 Language Features 8
Anonymous Types 9
Object Initializers 11
Collection Initializers 12
Partial Methods 13
Implicitly Typed Local Variables 14
Extensions 15
Expressions 16
Lambda Expressions 16
Query Expressions 18
Expression Trees 22
Summary 24
Chapter 2: LINQ to Objects 25
Array of Integers 25
Collection of Objects 27
Reading from Strings 29
Reading from Text Files 30
Summary 32
Chapter 3: LINQ to XML 33
Features 33
Classes and Hierarchy 34
XElement Class 36
XAttribute Class 36
XDocument Class 36
Other Classes 36
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Table of Contents
LINQ to XML with Other XML Technologies 38
LINQ with XmlReader 40
LINQ with XSLT 41
LINQ with MSXML 41
Functional Construction 41
XML Names 44
Loading and Traversing XML 45
Loading XML 46
Traversing XML 46
Data Manipulation 50
Inserting or Adding Elements to XML 50
Inserting or Adding XML Attributes 54
Deleting XML 55
Updating XML 56
Deleting XML Attributes 56
Updating XML Attributes 57
Outputting and Streaming XML 57
Streaming XML 58
Querying XML 59
Query Operators 59
Queries 60
Ancestors and Descendants 63
XML Transformation 64
Dictionaries 65
Convert Dictionary to XML 65
Create Dictionary from XML 66
Writing XML as Text Files and CSV Files 67
Reading from CSV Files 69
LINQ to XML Events 71
XML Literals and Embedded Expressions in Visual Basic 73
Summary 75
Chapter 4: LINQ to SQL 77
Working with Databases Using DataContext 77
Entity Classes 78
Attributes 81
Database Attribute 81
Table Attribute 82
Column Attribute 82
Association Attribute (Foreign Keys) 84
Relationships 85
Function Attribute 87
Parameter Attribute 88
Inheritance Mapping Attribute 88
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Table of Contents
Creating and Deleting Databases 89
DataContext Methods 90
Data Manipulation 93
LINQ to SQL Queries 96
Identifying Objects 99
Queries with Multiple Entities 100
Remote Queries and Local Queries 100
Deferred Loading 101
Immediate Loading 103
Projections 105
Constructing XML 106
Joins 107
Raw SQL Query 109
Query Result 109
Stored Procedures 110
User-Defined Functions 116
Class Generator Tool 117
Transactions 121
Handling Concurrency Conflicts 122
Object Relational Designer (O/R Designer) 123
Summary 140
Chapter 5: LINQ over DataSet 141
Loading Data into DataSets 142
Querying Datasets 144
Sequence Operator 146
Querying Typed DataSets 147
DataSet Query Operators 148
CopyToDataTable 149
LoadDataRow 149
Intersect 150
Union 150
Except 151
Field<T> 151
SetField<T> 152
Projection 152
Join 153
SequenceEqual 154
Skip 154
Distinct 154
Summary 154
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