SqlCommand.ExecuteXmlReader Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Sends the CommandText to the Connection and builds an XmlReader object.
public:
System::Xml::XmlReader ^ ExecuteXmlReader();public System.Xml.XmlReader ExecuteXmlReader ();member this.ExecuteXmlReader : unit -> System.Xml.XmlReaderPublic Function ExecuteXmlReader () As XmlReaderReturns
An XmlReader object.
Exceptions
A SqlDbType other than Binary or VarBinary was used when Value was set to Stream. For more information about streaming, see SqlClient Streaming Support.
-or-
A SqlDbType other than Char, NChar, NVarChar, VarChar, or Xml was used when Value was set to TextReader.
-or-
A SqlDbType other than Xml was used when Value was set to XmlReader.
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.
-or-
A timeout occurred during a streaming operation. For more information about streaming, see SqlClient Streaming Support.
The SqlConnection closed or dropped during a streaming operation. For more information about streaming, see SqlClient Streaming Support.
An error occurred in a Stream, XmlReader or TextReader object during a streaming operation. For more information about streaming, see SqlClient Streaming Support.
The Stream, XmlReader or TextReader object was closed during a streaming operation. For more information about streaming, see SqlClient Streaming Support.
Examples
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();
}
}
Public Sub CreateXMLReader(ByVal queryString As String, _
ByVal connectionString As String)
Using connection As New SqlConnection(connectionString)
connection.Open()
Dim command As New SqlCommand(queryString, connection)
Dim reader As System.Xml.XmlReader = command.ExecuteXmlReader
End Using
End Sub
Remarks
The XmlReader returned by this method does not support asynchronous operations.
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.
