Illustrated C# 2012

C H A P T E R  19

Introduction to LINQ

• What Is LINQ?
• LINQ Providers
• Method Syntax and Query Syntax
• Query Variables
• The Structure of Query Expressions
• The Standard Query Operators
• LINQ to XML

What Is LINQ?

In a relational database system, data is organized into nicely normalized tables and accessed with a very simple but powerful query language—SQL. SQL can work with any set of data in a database because the data is organized into tables, following strict rules.

In a program, as opposed to a database, however, data is stored in class objects or structs that are all vastly different. As a result, there’s been no general query language for retrieving data from data structures. The method of retrieving data from objects has always been custom-designed ...