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SqlCommand.ExecuteXmlReader Method

Sends the CommandText to the Connection and builds an XmlReader object.

Namespace:  System.Data.SqlClient
Assembly:  System.Data (in System.Data.dll)

public XmlReader ExecuteXmlReader()

Return Value

Type: System.Xml.XmlReader
An XmlReader object.

ExceptionCondition
SqlException

An exception occurred while executing the command against a locked row. This exception is not generated when you are using Microsoft .NET Framework version 1.0.

The CommandText property ordinarily specifies a Transact-SQL statement with a valid FOR XML clause. However, CommandText can also specify a statement that returns ntext or nvarchar data that contains valid XML, or the contents of a column defined with the xml data type.

A typical ExecuteXmlReader query can be formatted as in the following Microsoft Visual C# example:

SqlCommand command = new SqlCommand("SELECT * FROM dbo.Customers FOR XML AUTO, XMLDATA", SqlConn);
NoteNote

This type of query only works with Microsoft SQL Server 2000 or later. For more information see Guidelines for Using the FOR XML Clause in SQL Server Books Online.

When used with SQL Server 2005, this method can also be used to retrieve a single-row, single-column result set that contains XML data. In this case, if more than one row is returned, the ExecuteXmlReader method attaches the XmlReader to the value on the first row, and discards the rest of the result set.

When you use versions of SQL Server earlier than SQL Server 2005, while the XmlReader is being used the associated SqlConnection is busy serving the XmlReader. While in this state, no other operations can be performed on the SqlConnection other than closing it. This is the case until the Close method of the XmlReader is called. Starting with SQL Server 2005, the multiple active result set (MARS) feature allows for multiple actions using the same connection.

If you use ExecuteReader or BeginExecuteReader to access XML data, SQL Server will return any XML results greater than 2,033 characters in length in multiple rows of 2,033 characters each. To avoid this behavior, use ExecuteXmlReader or BeginExecuteXmlReader to read FOR XML queries. For more information, see article Q310378, "PRB: XML Data Is Truncated When You Use SqlDataReader," in the Microsoft Knowledge Base at http://support.microsoft.com.

The following example creates a SqlCommand and then executes it using ExecuteXmlReader. The example is passed a string that is a Transact-SQL FOR XML SELECT statement, and a string to use to connect to the data source.


private static void CreateXMLReader(string queryString,
    string connectionString)
{
    using (SqlConnection connection = new SqlConnection(
               connectionString))
    {
        connection.Open();
        SqlCommand command = new SqlCommand(queryString, connection);
        System.Xml.XmlReader reader = command.ExecuteXmlReader();
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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