LINQ for Visual C# 2008 (FirstPress)

Every C# programmer needs to learn about LINQ (Language-Integrated Query), Microsoft’s breakthrough technology for simplifying and unifying data access from any data source. It is the first step into the future of .NET programming. This book is a short yet comprehensive guide to the major features of LINQ, which provide significant enhancements to the next versions of C#, .NET, and ADO.NET that are available today for production programming. There is no better source for getting a head-start on the future of these technologies than this book. LINQ for Visual C# 2008 1 Copyright 197 Contents 3 What Is LINQ? 8 Why LINQ? 8 What You Need to Use LINQ 11 Resources 11 What’s Next? 12 Chapter 1: LINQ to Objects 13 Introduction 13 A Simple C# 3.0 LINQ to Objects Program 13 Extension Methods 15 Lambda Expressions 17 Expression Trees 18 Object Initialization Expressions 19 Anonymous Types 20 Implicitly Typed Local Variables 21 Query Evaluation Time 22 Standard Query Operators 26 Restriction Operator 33 Where 33 Projection Operators 36 Select 36 SelectMany 38 Join Operators 40 Join 40 GroupJoin 42 Grouping Operator 44 GroupBy 44 Ordering Operators 49 OrderBy and OrderByDescending 49 ThenBy and ThenByDescending 50 Reverse 53 Aggregate Operators 54 Count and LongCount 54 Sum 55 Min and Max 57 Average 59 Aggregate 61 Partitioning Operators 62 Take 62 Skip 63 TakeWhile 64 SkipWhile 65 Concatenation Operator 65 Concat 65 Element Operators 66 First, Last, FirstOrDefault, and LastOrDefault 67 Single and SingleOrDefault 69 ElementAt and ElementAtOrDefault 70 DefaultIfEmpty 71 Generation Operators 72 Empty 72 Range 72 Repeat 73 Quantifier Operators 74 All 74 Any 75 Contains 75 Equality Operator 76 SequenceEqual 76 Set Operators 77 Distinct 77 Intersect 78 Union 78 Except 79 Conversion Operators 80 OfType 80 Cast 80 ToSequence 81 ToArray 81 ToList 82 ToDictionary 83 ToLookup 84 Summary 86 Chapter 2: LINQ to ADO.NET 87 Introduction 87 Database Interaction 88 Mapping a Class to a Database Table 88 Mapping Fields and Properties to Table Columns 89 Creating a Data Context 94 Querying a Database with LINQ to SQL 96 Adding, Modifying, and Deleting Rows 100 DataContext: Advanced Features 103 Defining Relationships Between Entities 103 Using Two Related Entity Classes 112 Other LINQ to SQL Features 116 SQLMetal 116 The INotifyPropertyChanging Interface 119 Optimistic Concurrency and Database Transactions 121 Stored Procedures 127 User-Defined Functions 134 Database Creation 136 LINQ to SQL in Visual Studio 2008 138 A Linq to SQL File Designer Example 138 Debugging LINQ Applications 149 LINQ to DataSet 156 Summary 160 Chapter 3: LINQ to XML 161 Introduction 161 Querying XML 161 Searching for Attribute Values 165 The Descendants and Ancestors Methods 166 Querying XML for Content Type 167 Querying an XML Document That Uses Schemas 168 The ElementsBeforeSelf and ElementsAfterSelf Methods 171 Miscellaneous Functionalities 172 Parent 172 HasElements and HasAttributes 173 IsEmpty 174 Declaration 175 Creating and Modifying XML Documents 176 Creating an XML Document from Scratch 176 Using the XDeclaration Class 178 Using the XNamespace Class to Create an XML Document 179 Transforming XML 180 Loading and Saving XML 182 Modifying XML 184 Inserting Elements in an XML Document 184 Updating Elements in an XML Document 186 Deleting Elements from an XML Document 189 LINQ to XML and LINQ to SQL 191 Summary 195 Related Titles 196 Every C♯ programmer needs to learn about LINQ (Language-Integrated Query), Microsoft's breakthrough technology for simplifying and unifying data access from any data source. With LINQ, you can write more elegant and flexible code-not just to access databases and files, but to manipulate data structures and XML. This book is a short, yet comprehensive guide to the major features of LINQ and the significant enhancements introduced with .NET 3.5. There is no better source for getting a head-start on the future of these technologies than this book. A clear and comprehensive yet concise introduction to using LINQ in C♯ Covers LINQ to Objects, LINQ to SQL, LINQ to DataSet, and LINQ to XML Rich in working examples of LINQ in action Ideal for C♯ programmers at any level Every C# programmer needs to learn about LINQ (Language-lIntegrated Query), Microsoft's breakthrough technology for simplifying and unifying data access from any data source. With LINQ you can write more elegant and flexible code not just to access databases and files but to manipulate data structures and XML.This book is a short yet comprehensive guide to the major features of LINQ and the significant enhancements introduced with .NET 3.5. There is no better source for getting a head-start on the future of these technologies than this book.