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SqlCommand.BeginExecuteNonQuery Method

Definition

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

Overloads

BeginExecuteNonQuery()

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

BeginExecuteNonQuery(AsyncCallback, Object)

Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by this SqlCommand, given a callback procedure and state information.

BeginExecuteNonQuery()

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

public:
 IAsyncResult ^ BeginExecuteNonQuery();
public IAsyncResult BeginExecuteNonQuery ();
member this.BeginExecuteNonQuery : unit -> IAsyncResult
Public Function BeginExecuteNonQuery () As IAsyncResult

Returns

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

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.

Any error that occurred while executing the command text.

-or-

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

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

-or-

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 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.");
        Console.ReadLine();
    }

    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))
        {
            try
            {
                int count = 0;
                SqlCommand command = new SqlCommand(commandText, connection);
                connection.Open();

                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.
                    System.Threading.Thread.Sleep(100);
                }
                Console.WriteLine("Command complete. Affected {0} rows.",
                    command.EndExecuteNonQuery(result));
            }
            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";
    }
}
Imports System.Data.SqlClient

Module Module1

    Sub 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.
        Dim commandText As String = _
         "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.")
        Console.ReadLine()
    End Sub

    Private Sub RunCommandAsynchronously( _
     ByVal commandText As String, ByVal connectionString As String)

        ' 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 connection As New SqlConnection(connectionString)
            Try
                Dim count As Integer = 0
                Dim command As New SqlCommand(commandText, connection)
                connection.Open()
                Dim result As IAsyncResult = command.BeginExecuteNonQuery()
                While Not 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.
                    Threading.Thread.Sleep(100)
                    count += 1
                End While
                Console.WriteLine("Command complete. Affected {0} rows.", _
                    command.EndExecuteNonQuery(result))
            Catch ex As SqlException
                Console.WriteLine("Error ({0}): {1}", ex.Number, ex.Message)
            Catch ex As InvalidOperationException
                Console.WriteLine("Error: {0}", ex.Message)
            Catch ex As Exception
                ' You might want to pass these errors
                ' back out to the caller.
                Console.WriteLine("Error: {0}", ex.Message)
            End Try
        End Using
    End Sub

    Private Function GetConnectionString() As String
        ' 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"
    End Function
End Module

Remarks

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.

This method ignores the CommandTimeout property.

See also

Applies to

BeginExecuteNonQuery(AsyncCallback, Object)

Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by this SqlCommand, given a callback procedure and state information.

public:
 IAsyncResult ^ BeginExecuteNonQuery(AsyncCallback ^ callback, System::Object ^ stateObject);
public IAsyncResult BeginExecuteNonQuery (AsyncCallback callback, object stateObject);
member this.BeginExecuteNonQuery : AsyncCallback * obj -> IAsyncResult
Public Function BeginExecuteNonQuery (callback As AsyncCallback, stateObject As Object) As IAsyncResult

Parameters

callback
AsyncCallback

An AsyncCallback delegate that is invoked when the command's execution has completed. Pass null (Nothing in Microsoft Visual Basic) to indicate that no callback is required.

stateObject
Object

A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback procedure using the AsyncState property.

Returns

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

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.

Any error that occurred while executing the command text.

-or-

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

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

-or-

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 Windows application demonstrates the use of the BeginExecuteNonQuery method, executing a Transact-SQL statement that includes a delay of several seconds (emulating a long-running command).

This example demonstrates many important techniques. This includes calling a method that interacts with the form from a separate thread. In addition, this example demonstrates how you must block users from executing a command multiple times concurrently, and how you must make sure that the form does not close before the callback procedure is called.

To set up this example, create a new Windows application. Put a Button control and a Label control on the form (accepting the default name for each control). Add the following code to the form's class, modifying the connection string as needed for your environment.

using System.Data.SqlClient;

namespace Microsoft.AdoDotNet.CodeSamples
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        // Hook up the form's Load event handler (you can double-click on
        // the form's design surface in Visual Studio), and then add
        // this code to the form's class:
        private void Form1_Load(object sender, EventArgs e)
        {
            this.button1.Click += new System.EventHandler(this.button1_Click);
            this.FormClosing += new System.Windows.Forms.
                FormClosingEventHandler(this.Form1_FormClosing);
        }

        // You need this delegate in order to display text from a thread
        // other than the form's thread. See the HandleCallback
        // procedure for more information.
        // This same delegate matches both the DisplayStatus
        // and DisplayResults methods.
        private delegate void DisplayInfoDelegate(string Text);

        // This flag ensures that the user does not attempt
        // to restart the command or close the form while the
        // asynchronous command is executing.
        private bool isExecuting;

        // This example maintains the connection object
        // externally, so that it is available for closing.
        private SqlConnection connection;

        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=true;" +
                "Initial Catalog=AdventureWorks; Asynchronous Processing=true";
        }

        private void DisplayStatus(string Text)
        {
            this.label1.Text = Text;
        }

        private void DisplayResults(string Text)
        {
            this.label1.Text = Text;
            DisplayStatus("Ready");
        }

        private void Form1_FormClosing(object sender,
            System.Windows.Forms.FormClosingEventArgs e)
        {
            if (isExecuting)
            {
                MessageBox.Show(this, "Cannot close the form until " +
                    "the pending asynchronous command has completed. Please wait...");
                e.Cancel = true;
            }
        }

        private void button1_Click(object sender, System.EventArgs e)
        {
            if (isExecuting)
            {
                MessageBox.Show(this,
                    "Already executing. Please wait until the current query " +
                    "has completed.");
            }
            else
            {
                SqlCommand command = null;
                try
                {
                    DisplayResults("");
                    DisplayStatus("Connecting...");
                    connection = new SqlConnection(GetConnectionString());
                    // To emulate a long-running query, wait for
                    // a few seconds before working with the data.
                    // This command does not do much, but that's the point--
                    // it does not change your data, in the long run.
                    string commandText =
                        "WAITFOR DELAY '0:0:05';" +
                        "UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " +
                        "WHERE ReorderPoint Is Not Null;" +
                        "UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " +
                        "WHERE ReorderPoint Is Not Null";

                    command = new SqlCommand(commandText, connection);
                    connection.Open();

                    DisplayStatus("Executing...");
                    isExecuting = true;
                    // Although it is not required that you pass the
                    // SqlCommand object as the second parameter in the
                    // BeginExecuteNonQuery call, doing so makes it easier
                    // to call EndExecuteNonQuery in the callback procedure.
                    AsyncCallback callback = new AsyncCallback(HandleCallback);
                    command.BeginExecuteNonQuery(callback, command);
                }
                catch (Exception ex)
                {
                    isExecuting = false;
                    DisplayStatus(string.Format("Ready (last error: {0})", ex.Message));
                    if (connection != null)
                    {
                        connection.Close();
                    }
                }
            }
        }

        private void HandleCallback(IAsyncResult result)
        {
            try
            {
                // Retrieve the original command object, passed
                // to this procedure in the AsyncState property
                // of the IAsyncResult parameter.
                SqlCommand command = (SqlCommand)result.AsyncState;
                int rowCount = command.EndExecuteNonQuery(result);
                string rowText = " rows affected.";
                if (rowCount == 1)
                {
                    rowText = " row affected.";
                }
                rowText = rowCount + rowText;

                // You may not interact with the form and its contents
                // from a different thread, and this callback procedure
                // is all but guaranteed to be running from a different thread
                // than the form. Therefore you cannot simply call code that
                // displays the results, like this:
                // DisplayResults(rowText)

                // Instead, you must call the procedure from the form's thread.
                // One simple way to accomplish this is to call the Invoke
                // method of the form, which calls the delegate you supply
                // from the form's thread.
                DisplayInfoDelegate del = new DisplayInfoDelegate(DisplayResults);
                this.Invoke(del, rowText);
            }
            catch (Exception ex)
            {
                // Because you are now running code in a separate thread,
                // if you do not handle the exception here, none of your other
                // code catches the exception. Because none of
                // your code is on the call stack in this thread, there is nothing
                // higher up the stack to catch the exception if you do not
                // handle it here. You can either log the exception or
                // invoke a delegate (as in the non-error case in this
                // example) to display the error on the form. In no case
                // can you simply display the error without executing a delegate
                // as in the try block here.

                // You can create the delegate instance as you
                // invoke it, like this:
                this.Invoke(new DisplayInfoDelegate(DisplayStatus),
                    String.Format("Ready(last error: {0}", ex.Message));
            }
            finally
            {
                isExecuting = false;
                if (connection != null)
                {
                    connection.Close();
                }
            }
        }
    }
}
Imports System.Data.SqlClient

Public Class Form1
    ' Add this code to the form's class:
    ' You need this delegate in order to display text from a thread
    ' other than the form's thread. See the HandleCallback
    ' procedure for more information.
    ' This same delegate matches both the DisplayStatus 
    ' and DisplayResults methods.
    Private Delegate Sub DisplayInfoDelegate(ByVal Text As String)

    ' This flag ensures that the user does not attempt
    ' to restart the command or close the form while the 
    ' asynchronous command is executing.
    Private isExecuting As Boolean

    ' This example maintains the connection object 
    ' externally, so that it is available for closing.
    Private connection As SqlConnection

    Private Function GetConnectionString() As String
        ' 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=true;" & _
          "Initial Catalog=AdventureWorks; Asynchronous Processing=true"
    End Function

    Private Sub DisplayStatus(ByVal Text As String)
        Me.Label1.Text = Text
    End Sub

    Private Sub DisplayResults(ByVal Text As String)
        Me.Label1.Text = Text
        DisplayStatus("Ready")
    End Sub

    Private Sub Form1_FormClosing(ByVal sender As Object, _
        ByVal e As System.Windows.Forms.FormClosingEventArgs) _
        Handles Me.FormClosing
        If isExecuting Then
            MessageBox.Show(Me, "Cannot close the form until " & _
                "the pending asynchronous command has completed. Please wait...")
            e.Cancel = True
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button1.Click
        If isExecuting Then
            MessageBox.Show(Me, _
               "Already executing. Please wait until the current query " & _
                "has completed.")
        Else
            Dim command As SqlCommand
            Try
                DisplayResults("")
                DisplayStatus("Connecting...")
                connection = New SqlConnection(GetConnectionString())
                ' To emulate a long-running query, wait for 
                ' a few seconds before working with the data.
                ' This command does not do much, but that's the point--
                ' it does not change your data, in the long run.
                Dim commandText As String = _
                    "WAITFOR DELAY '0:0:05';" & _
                    "UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " & _
                    "WHERE ReorderPoint Is Not Null;" & _
                    "UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " & _
                    "WHERE ReorderPoint Is Not Null"

                command = New SqlCommand(commandText, connection)
                connection.Open()

                DisplayStatus("Executing...")
                isExecuting = True
                ' Although it is not required that you pass the 
                ' SqlCommand object as the second parameter in the 
                ' BeginExecuteNonQuery call, doing so makes it easier
                ' to call EndExecuteNonQuery in the callback procedure.
                Dim callback As New AsyncCallback(AddressOf HandleCallback)
                command.BeginExecuteNonQuery(callback, command)

            Catch ex As Exception
                isExecuting = False
                DisplayStatus(String.Format("Ready (last error: {0})", ex.Message))
                If connection IsNot Nothing Then
                    connection.Close()
                End If
            End Try
        End If
    End Sub

    Private Sub HandleCallback(ByVal result As IAsyncResult)
        Try
            ' Retrieve the original command object, passed
            ' to this procedure in the AsyncState property
            ' of the IAsyncResult parameter.
            Dim command As SqlCommand = CType(result.AsyncState, SqlCommand)
            Dim rowCount As Integer = command.EndExecuteNonQuery(result)
            Dim rowText As String = " rows affected."
            If rowCount = 1 Then
                rowText = " row affected."
            End If
            rowText = rowCount & rowText

            ' You may not interact with the form and its contents
            ' from a different thread, and this callback procedure
            ' is all but guaranteed to be running from a different thread
            ' than the form. Therefore you cannot simply call code that 
            ' displays the results, like this:
            ' DisplayResults(rowText)

            ' Instead, you must call the procedure from the form's thread.
            ' One simple way to accomplish this is to call the Invoke
            ' method of the form, which calls the delegate you supply
            ' from the form's thread. 
            Dim del As New DisplayInfoDelegate(AddressOf DisplayResults)
            Me.Invoke(del, rowText)

        Catch ex As Exception
            ' Because you are now running code in a separate thread, 
            ' if you do not handle the exception here, none of your other
            ' code catches the exception. Because none of your code
            ' is on the call stack in this thread, there is nothing
            ' higher up the stack to catch the exception if you do not 
            ' handle it here. You can either log the exception or 
            ' invoke a delegate (as in the non-error case in this 
            ' example) to display the error on the form. In no case
            ' can you simply display the error without executing a delegate
            ' as in the Try block here. 

            ' You can create the delegate instance as you 
            ' invoke it, like this:
            Me.Invoke(New DisplayInfoDelegate(AddressOf DisplayStatus), _
                String.Format("Ready(last error: {0}", ex.Message))
        Finally
            isExecuting = False
            If connection IsNot Nothing Then
                connection.Close()
            End If
        End Try
    End Sub
End Class

Remarks

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.

The callback parameter lets you specify an AsyncCallback delegate that is called when the statement has completed. You can call the EndExecuteNonQuery method from within this delegate procedure, or from any other location within your application. In addition, you can pass any object in the asyncStateObject parameter, and your callback procedure can retrieve this information using the AsyncState property.

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 the callback procedure executes from within a background thread supplied by the Microsoft .NET common language runtime, it is very important that you take a rigorous approach to handling cross-thread interactions from within your applications. For example, you must not interact with a form's contents from within your callback procedure; should you have to update the form, you must switch back to the form's thread in order to do your work. The example in this topic demonstrates this behavior.

All errors that occur during the execution of the operation are thrown as exceptions in the callback procedure. You must handle the exception in the callback procedure, not in the main application. See the example in this topic for additional information on handling exceptions in the callback procedure.

This method ignores the CommandTimeout property.

See also

Applies to