How to use LINQ to XML to create and to query an XML document

This article describes an All-In-One Code Framework sample that is available for downloading. This sample includes a step-by-step guide about how to create and to query an XML document whose data is from LINQ to Objects (in-memory objects) and from LINQ to SQL (SQL Server databases). The Visual Basic.NET version also uses the XML literals feature, which is introduced in Visual Basic.NET 2008.

Difficulty level

Download information

To download this code sample, click the following link:

  

Technical overview

LINQ to XML provides an in-memory XML programming interface that leverages the Microsoft .NET Language Integrated Query (LINQ) Framework. LINQ to XML uses the latest .NET Framework language capabilities and is comparable to an updated, redesigned Document Object Model (DOM) XML programming interface.

The most important advantage of LINQ to XML is its integration with LINQ. This integration lets you write queries on the in-memory XML document to retrieve collections of elements and of attributes. The query capability of LINQ to XML is comparable in functionality (although not in syntax) to XPath and to XQuery. The integration of LINQ into Visual C# 2008 provides better support for typing, compile-time checking, and debugging.

Another advantage of LINQ to XML is the ability to use query results as parameters for XElement and XAttribute object constructors. This ability enables a powerful approach to creating XML trees. This approach is called functional construction and enables developers to easily transform XML trees from on shape to another.

In Visual Basic.NET, another advantage of LINQ to XML is the XML literals feature, which allows you to incorporate XML directly into Visual Basic code. The XML literal syntax represents LINQ to XML objects and is similar to XML 1.0 syntax. This similarity makes XML elements and documents easier to create programmatically because this similarity would give your code the same structure as the final XML.

Note For more information about how to create and then deploy the sample application, see the Readme.txt file that is included in the download package.

Technology category

• LINQ to XML

Languages

This code sample contains the following programming languages.

Prerequisites

• You must first deploy the SQLServer2005DB database that is generated by the SQLServer2005DB database project. Deploy the SQLServer2005DB database to your SQL Server instance, and then modify the connection string in the App.config file according to your database instance and login account.
• This sample application was created by using Visual Studio 2008 with Service Pack 1 installed.

Tags

• LINQ to XML, XML literals

What is All-In-One Code Framework?

All-In-One Code Framework uses code samples in different programming languages to illustrate most Microsoft development techniques. Each code sample is carefully selected, composed, and documented to show common code scenarios. For more information about All-In-One Code Framework, visit the following All-In-One Code Framework Web site:

How to find more All-In-One Code Framework samples

To find more All-In-One Code Framework samples, search for "kbcodefx" together with related keywords on the Microsoft support Web site. Or, visit the following Microsoft Web site:

For more information, visit the following Microsoft Developer Network (MSDN) Web sites:

• LINQ to XML Overview (http://msdn.microsoft.com/en-us/library/bb387061.aspx)
• XML Literals Overview (http://msdn.microsoft.com/en-us/library/bb384629.aspx)
• How to: Create a Document with Namespaces (C#) (LINQ to XML) (http://msdn.microsoft.com/en-us/library/bb387075.aspx)
• Scope of Default Namespaces in C# (LINQ to XML) (http://msdn.microsoft.com/en-us/library/bb943852.aspx)
• Namespaces in C# (LINQ to XML) (http://msdn.microsoft.com/en-us/library/bb387042.aspx)
• Namespaces in Visual Basic (LINQ to XML) (http://msdn.microsoft.com/en-us/library/bb387016.aspx)
• Creating XML in Visual Basic (http://msdn.microsoft.com/en-us/library/bb384808.aspx)
• Embedded Expressions in XML (http://msdn.microsoft.com/en-us/library/bb384964.aspx)