SqlCommand.BeginExecuteNonQuery Method ()

Note: This method is new in the .NET Framework version 2.0.

Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by this SqlCommand.

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

public IAsyncResult BeginExecuteNonQuery ()
public IAsyncResult BeginExecuteNonQuery ()
public function BeginExecuteNonQuery () : IAsyncResult

Return Value

An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndExecuteNonQuery, which returns the number of affected rows.

Exception typeCondition


Any error that occurred while executing the command text.


The name/value pair "Asynchronous Processing=true" was not included within the connection string defining the connection for this SqlCommand.

The BeginExecuteNonQuery method starts the process of asynchronously executing a Transact-SQL statement or stored procedure that does not return rows, so that other tasks can run concurrently while the statement is executing. When the statement has completed, developers must call the EndExecuteNonQuery method to finish the operation. The BeginExecuteNonQuery method returns immediately, but until the code executes the corresponding EndExecuteNonQuery method call, it must not execute any other calls that start a synchronous or asynchronous execution against the same SqlCommand object. Calling the EndExecuteNonQuery before the command's execution is completed causes the SqlCommand object to block until the execution is finished.

Note that the command text and parameters are sent to the server synchronously. If a large command or many parameters are sent, this method may block during writes. After the command is sent, the method returns immediately without waiting for an answer from the server--that is, reads are asynchronous.

Because this overload does not support a callback procedure, developers must either poll to determine whether the command has completed, using the IsCompleted property of the IAsyncResult returned by the BeginExecuteNonQuery method; or wait for the completion of one or more commands using the AsyncWaitHandle property of the returned IAsyncResult.

The following console application creates updates data within the AdventureWorks sample database, doing its work asynchronously. In order to emulate a long-running process, this example inserts a WAITFOR statement in the command text. Normally, you would not take efforts to make your commands run slower, but doing this in this case makes it easier to demonstrate the asynchronous behavior.

using System.Data.SqlClient;

class Class1
    static void Main()
        // This is a simple example that demonstrates the usage of the 
        // BeginExecuteNonQuery functionality.
        // The WAITFOR statement simply adds enough time to prove the 
        // asynchronous nature of the command.
        string commandText = 
            "UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " + 
            "WHERE ReorderPoint Is Not Null;" + 
            "WAITFOR DELAY '0:0:3';" + 
            "UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " + 
            "WHERE ReorderPoint Is Not Null";

        RunCommandAsynchronously(commandText, GetConnectionString());

        Console.WriteLine("Press ENTER to continue.");

    private static void RunCommandAsynchronously(
        string commandText, string connectionString)
        // Given command text and connection string, asynchronously execute
        // the specified command against the connection. For this example,
        // the code displays an indicator as it is working, verifying the 
        // asynchronous behavior. 
        using (SqlConnection connection = 
                   new SqlConnection(connectionString))
                int count = 0;
                SqlCommand command = new SqlCommand(commandText, connection);

                IAsyncResult result = command.BeginExecuteNonQuery();
                while (!result.IsCompleted)
                    Console.WriteLine("Waiting ({0)", count++);
                    // Wait for 1/10 second, so the counter
                    // does not consume all available resources 
                    // on the main thread.
                Console.WriteLine("Command complete. Affected {0 rows.", 
            catch (SqlException ex)
                Console.WriteLine("Error ({0): {1", ex.Number, ex.Message);
            catch (InvalidOperationException ex)
                Console.WriteLine("Error: {0", ex.Message);
            catch (Exception ex)
                // You might want to pass these errors
                // back out to the caller.
                Console.WriteLine("Error: {0", ex.Message);

    private static string GetConnectionString()
        // To avoid storing the connection string in your code,            
        // you can retrieve it from a configuration file. 

        // If you have not included "Asynchronous Processing=true" in the
        // connection string, the command is not able
        // to execute asynchronously.
        return "Data Source=(local);Integrated Security=SSPI;" +
            "Initial Catalog=AdventureWorks; Asynchronous Processing=true";

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0