Introduction to LINQ

LINQ stands for Language-Integrated Query that is a set of extensions to the .Net 3.5 framework and is also available in its later on versions. In the previous versions of .Net framework for example 2.0, 1.1 we were using traditional way to implement the different types of query languages such SQL for SQL database, XML document parsing and various types of web services. But the LINQ has introduced a new way of applying powerful query capabilities integrated into the extended form of C# and VB.Net languages. LINQ has introduced a standard platform for querying and updating the data stored in any kind of data store. Microsoft has designed it in such a way that it can be used with .Net based collections, SQL Server database, ADO.Net datasets and XML documents. The .Net framework includes the LINQ provider assemblies that provide all the extended features of LINQ in the language syntax of C# and Visual Basic.

LINQ Implementation Walkthrough

The extensibility of the data query architecture is used in the LINQ project also to provide implementation flexibility that works over both XML documents and SQL datasets. The query operators over XML use an efficient, easy-to-use, in-memory XML parsing facility that provide XPath/XQuery functionality in the language syntax of C# and VB.Net. This LINQ operations functionality is also called LINQ to XML. The query operators over relational data build on the integration of SQL-based schema definitions into the common language runtime system that provides strong typing facility for querying and updating the relational data while retaining the expressive power and performance of the integrated queries. This LINQ operations functionality is also called LINQ to SQL.

Let's see a simple C# program created using language integrated query:

int[] myNumbers = { 10, 22, 13, 44, 25, 31, 5 };
 
IEnumerable<string> query = from i in myNumbers
                            orderby i
                            select i.ToString();
 
foreach (string item in query)
{
    Response.Output.Write("{0}<br />", item);
}

.NET Language-Integrated Query works with standard query operators that allow traversal, filter, and projection operations that can be implemented directly in any .NET-based programming language. The standard query operators allow queries to be applied to any IEnumerable<T>-based data source.

Continue to next tutorial: Introduction to LINQ queries in C# to learn about the query actions and their types of executions.