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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
InvalidCastException

A SqlDbType other than Binary or VarBinary was used when Value was set to Stream. For more information about streaming, see SqlClient Streaming Support.

A SqlDbType other than Char, NChar, NVarChar, VarChar, or Xml was used when Value was set to TextReader.

A SqlDbType other than Xml was used when Value was set to XmlReader.

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.

A timeout occurred during a streaming operation. For more information about streaming, see SqlClient Streaming Support.

InvalidOperationException

The SqlConnection closed or dropped during a streaming operation. For more information about streaming, see SqlClient Streaming Support.

IOException

An error occurred in a Stream, XmlReader or TextReader object during a streaming operation. For more information about streaming, see SqlClient Streaming Support.

ObjectDisposedException

The Stream, XmlReader or TextReader object was closed during a streaming operation. For more information about streaming, see SqlClient Streaming Support.

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);

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.

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: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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