SqlCommand.BeginExecuteNonQuery SqlCommand.BeginExecuteNonQuery SqlCommand.BeginExecuteNonQuery SqlCommand.BeginExecuteNonQuery Method

Définition

Lance l’exécution asynchrone de l’instruction ou la procédure stockée Transact-SQL qui est décrite par ce SqlCommand.Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by this SqlCommand.

Surcharges

BeginExecuteNonQuery() BeginExecuteNonQuery() BeginExecuteNonQuery() BeginExecuteNonQuery()

Lance l’exécution asynchrone de l’instruction ou la procédure stockée Transact-SQL qui est décrite par ce SqlCommand.Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by this SqlCommand.

BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object)

Lance l’exécution asynchrone de l’instruction Transact-SQL ou de la procédure stockée qui est décrite par ce SqlCommand, pour une procédure de rappel et des informations d’état données.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() BeginExecuteNonQuery() BeginExecuteNonQuery() BeginExecuteNonQuery()

Lance l’exécution asynchrone de l’instruction ou la procédure stockée Transact-SQL qui est décrite par ce SqlCommand.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

Retours

IAsyncResult pouvant être utilisé pour interroger ou attendre des résultats, ou les deux ; cette valeur est également requise pour appeler EndExecuteNonQuery(IAsyncResult), qui retourne le nombre de lignes affectées.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

Un SqlDbType autre que Binary ou VarBinary a été utilisé quand Value avait la valeur Stream.A SqlDbType other than Binary or VarBinary was used when Value was set to Stream. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

- ou --or-

Un SqlDbType autre que Char, NChar, NVarChar, VarChar ou Xml a été utilisé quand Value avait la valeur TextReader.A SqlDbType other than Char, NChar, NVarChar, VarChar, or Xml was used when Value was set to TextReader.

- ou --or-

Un SqlDbType autre que Xml a été utilisé quand Value avait la valeur XmlReader.A SqlDbType other than Xml was used when Value was set to XmlReader.

Toute erreur qui s’est produite pendant l’exécution du texte de la commande.Any error that occurred while executing the command text.

- ou --or-

Un délai d’attente a été dépassé pendant une opération de diffusion en continu.A timeout occurred during a streaming operation. Pour plus d’informations sur la diffusion en continu, consultez Prise en charge de la diffusion en continu pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

La paire nom/valeur "Asynchronous Processing=true" n’était pas incluse dans la chaîne de connexion qui définissait la connexion pour ce SqlCommand.The name/value pair "Asynchronous Processing=true" was not included within the connection string defining the connection for this SqlCommand.

- ou --or-

La SqlConnection a été fermée ou supprimée pendant une opération de diffusion en continu.The SqlConnection closed or dropped during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

Une erreur s’est produite dans un objet Stream, XmlReader ou TextReader pendant une opération de diffusion en continu.An error occurred in a Stream, XmlReader or TextReader object during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

L’objet Stream, XmlReader ou TextReader a été fermé pendant une opération de diffusion en continu.The Stream, XmlReader or TextReader object was closed during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

Exemples

L’application console suivante crée des données de mise à jour dans l’exemple de base de données AdventureWorks , en procédant de manière asynchrone.The following console application creates updates data within the AdventureWorks sample database, doing its work asynchronously. Pour émuler un processus de longue durée, cet exemple insère une instruction WAITFOR dans le texte de commande.In order to emulate a long-running process, this example inserts a WAITFOR statement in the command text. En règle générale, vous n’avez pas l’habitude d’exécuter vos commandes plus lentement, mais cela permet d’illustrer plus facilement le comportement asynchrone.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

Remarques

La BeginExecuteNonQuery méthode démarre le processus d’exécution asynchrone d’une instruction Transact-SQLTransact-SQL ou d’une procédure stockée qui ne retourne pas de lignes, afin que d’autres tâches puissent s’exécuter simultanément pendant l’exécution de l’instruction.The BeginExecuteNonQuery method starts the process of asynchronously executing a Transact-SQLTransact-SQL statement or stored procedure that does not return rows, so that other tasks can run concurrently while the statement is executing. Lorsque l’instruction est terminée, les développeurs doivent appeler EndExecuteNonQuery la méthode pour terminer l’opération.When the statement has completed, developers must call the EndExecuteNonQuery method to finish the operation. La BeginExecuteNonQuery méthode est retournéeCommandTimeout immédiatement (n’a BeginExecuteNonQueryaucun effet sur), mais jusqu’à ce que EndExecuteNonQuery le code exécute l’appel de méthode correspondant, il ne doit pas exécuter d’autres appels qui démarrent une exécution synchrone ou asynchrone sur le même SqlCommand objet.The BeginExecuteNonQuery method returns immediately (CommandTimeout has no effect on BeginExecuteNonQuery), 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. L’appel de SqlCommand avantlafindel’exécutiondelacommandeentraîneleblocagedel’objetjusqu’àcequel'EndExecuteNonQuery exécution soit terminée.Calling the EndExecuteNonQuery before the command's execution is completed causes the SqlCommand object to block until the execution is finished.

Notez que le texte de la commande et les paramètres sont envoyés au serveur de façon synchrone.Note that the command text and parameters are sent to the server synchronously. Si une ou plusieurs de ces commandes sont envoyées, cette méthode peut se bloquer pendant les écritures.If a large command or many parameters are sent, this method may block during writes. Une fois la commande envoyée, la méthode retourne immédiatement sans attendre une réponse du serveur, c’est-à-dire que les lectures sont asynchrones.After the command is sent, the method returns immediately without waiting for an answer from the server--that is, reads are asynchronous.

Étant donné que cette surcharge ne prend pas en charge une procédure de rappel, les développeurs doivent effectuer une interrogation pour déterminer IsCompleted si la commande IAsyncResult est terminée, BeginExecuteNonQuery à l’aide de la propriété du retourné par la méthode, ou attendre la fin de une ou plusieurs commandes à l' AsyncWaitHandle aide de la propriété IAsyncResultdu retourné.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.

Voir aussi

BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object) BeginExecuteNonQuery(AsyncCallback, Object)

Lance l’exécution asynchrone de l’instruction Transact-SQL ou de la procédure stockée qui est décrite par ce SqlCommand, pour une procédure de rappel et des informations d’état données.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

Paramètres

callback
AsyncCallback AsyncCallback AsyncCallback AsyncCallback

Délégué AsyncCallback qui est appelé une fois l’exécution de la commande terminée.An AsyncCallback delegate that is invoked when the command's execution has completed. Passez null (Nothing en Microsoft Visual Basic) pour indiquer qu’aucun rappel n’est requis.Pass null (Nothing in Microsoft Visual Basic) to indicate that no callback is required.

stateObject
Object Object Object Object

Objet d'état défini par l'utilisateur qui est transmis à la procédure de rappel.A user-defined state object that is passed to the callback procedure. Récupérez cet objet à partir de la procédure de rappel à l’aide de la propriété AsyncState.Retrieve this object from within the callback procedure using the AsyncState property.

Retours

IAsyncResult pouvant être utilisé pour interroger ou attendre des résultats, ou les deux ; cette valeur est également requise pour appeler EndExecuteNonQuery(IAsyncResult), qui retourne le nombre de lignes affectées.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

Un SqlDbType autre que Binary ou VarBinary a été utilisé quand Value avait la valeur Stream.A SqlDbType other than Binary or VarBinary was used when Value was set to Stream. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

- ou --or-

Un SqlDbType autre que Char, NChar, NVarChar, VarChar ou Xml a été utilisé quand Value avait la valeur TextReader.A SqlDbType other than Char, NChar, NVarChar, VarChar, or Xml was used when Value was set to TextReader.

- ou --or-

Un SqlDbType autre que Xml a été utilisé quand Value avait la valeur XmlReader.A SqlDbType other than Xml was used when Value was set to XmlReader.

Toute erreur qui s’est produite pendant l’exécution du texte de la commande.Any error that occurred while executing the command text.

ou-or-

Un délai d’attente a été dépassé pendant une opération de diffusion en continu.A timeout occurred during a streaming operation. Pour plus d’informations sur la diffusion en continu, consultez Prise en charge de la diffusion en continu pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

La paire nom/valeur "Asynchronous Processing=true" n’était pas incluse dans la chaîne de connexion qui définissait la connexion pour ce SqlCommand.The name/value pair "Asynchronous Processing=true" was not included within the connection string defining the connection for this SqlCommand.

ou-or-

La SqlConnection a été fermée ou supprimée pendant une opération de diffusion en continu.The SqlConnection closed or dropped during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

Une erreur s’est produite dans un objet Stream, XmlReader ou TextReader pendant une opération de diffusion en continu.An error occurred in a Stream, XmlReader or TextReader object during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

L’objet Stream, XmlReader ou TextReader a été fermé pendant une opération de diffusion en continu.The Stream, XmlReader or TextReader object was closed during a streaming operation. Pour plus d’informations sur le streaming, consultez Prise en charge du streaming pour SqlClient.For more information about streaming, see SqlClient Streaming Support.

Exemples

L’application Windows suivante illustre l’utilisation de la BeginExecuteNonQuery méthode, en exécutant une instruction Transact-SQL qui comprend un délai de plusieurs secondes (émulation d’une commande longue).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).

Cet exemple illustre de nombreuses techniques importantes.This example demonstrates many important techniques. Cela comprend l’appel d’une méthode qui interagit avec le formulaire à partir d’un thread distinct.This includes calling a method that interacts with the form from a separate thread. En outre, cet exemple montre comment vous devez empêcher les utilisateurs d’exécuter une commande plusieurs fois simultanément, et comment vous devez vous assurer que le formulaire ne se ferme pas avant l’appel de la procédure de rappel.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.

Pour configurer cet exemple, créez une application Windows.To set up this example, create a new Windows application. Placez un Button contrôle et un Label contrôle sur le formulaire (en acceptant le nom par défaut pour chaque contrôle).Put a Button control and a Label control on the form (accepting the default name for each control). Ajoutez le code suivant à la classe du formulaire, en modifiant la chaîne de connexion en fonction des besoins de votre environnement.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

Remarques

La BeginExecuteNonQuery méthode démarre le processus d’exécution asynchrone d’une instruction Transact-SQL ou d’une procédure stockée qui ne retourne pas de lignes, afin que d’autres tâches puissent s’exécuter simultanément pendant l’exécution de l’instruction.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. Lorsque l’instruction est terminée, les développeurs doivent appeler EndExecuteNonQuery la méthode pour terminer l’opération.When the statement has completed, developers must call the EndExecuteNonQuery method to finish the operation. La BeginExecuteNonQuery méthode est retournéeCommandTimeout immédiatement (n’a BeginExecuteNonQueryaucun effet sur), mais jusqu’à ce que EndExecuteNonQuery le code exécute l’appel de méthode correspondant, il ne doit pas exécuter d’autres appels qui démarrent une exécution synchrone ou asynchrone sur le même SqlCommand objet.The BeginExecuteNonQuery method returns immediately (CommandTimeout has no effect on BeginExecuteNonQuery), 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. L’appel de SqlCommand avantlafindel’exécutiondelacommandeentraîneleblocagedel’objetjusqu’àcequel'EndExecuteNonQuery exécution soit terminée.Calling the EndExecuteNonQuery before the command's execution is completed causes the SqlCommand object to block until the execution is finished.

Le callback paramètre vous permet de spécifier AsyncCallback un délégué qui est appelé lorsque l’instruction est terminée.The callback parameter lets you specify an AsyncCallback delegate that is called when the statement has completed. Vous pouvez appeler la EndExecuteNonQuery méthode à partir de cette procédure déléguée, ou à partir de tout autre emplacement au sein de votre application.You can call the EndExecuteNonQuery method from within this delegate procedure, or from any other location within your application. En outre, vous pouvez passer n’importe quel objet asyncStateObject dans le paramètre et votre procédure de rappel peut récupérer ces informations AsyncState à l’aide de la propriété.In addition, you can pass any object in the asyncStateObject parameter, and your callback procedure can retrieve this information using the AsyncState property.

Notez que le texte de la commande et les paramètres sont envoyés au serveur de façon synchrone.Note that the command text and parameters are sent to the server synchronously. Si une ou plusieurs de ces commandes sont envoyées, cette méthode peut se bloquer pendant les écritures.If a large command or many parameters are sent, this method may block during writes. Une fois la commande envoyée, la méthode retourne immédiatement sans attendre une réponse du serveur, c’est-à-dire que les lectures sont asynchrones.After the command is sent, the method returns immediately without waiting for an answer from the server--that is, reads are asynchronous.

Étant donné que la procédure de rappel s’exécute à partir d’un thread d’arrière-plan fourni par le common language runtime Microsoft .NET, il est très important de prendre une approche rigoureuse pour gérer les interactions entre les threads à partir de vos applications.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. Par exemple, vous ne devez pas interagir avec le contenu d’un formulaire à partir de votre procédure de rappel. Si vous devez mettre à jour le formulaire, vous devez revenir au thread du formulaire pour effectuer votre travail.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. L’exemple de cette rubrique illustre ce comportement.The example in this topic demonstrates this behavior.

Toutes les erreurs qui se produisent pendant l’exécution de l’opération sont levées en tant qu’exceptions dans la procédure de rappel.All errors that occur during the execution of the operation are thrown as exceptions in the callback procedure. Vous devez gérer l’exception dans la procédure de rappel, et non dans l’application principale.You must handle the exception in the callback procedure, not in the main application. Pour plus d’informations sur la gestion des exceptions dans la procédure de rappel, consultez l’exemple de cette rubrique.See the example in this topic for additional information on handling exceptions in the callback procedure.

Voir aussi

S’applique à