TransactionScope.Complete Metodo

Definizione

Indica che sono state completate tutte le operazioni all'interno dell'ambito.Indicates that all operations within the scope are completed successfully.

public:
 void Complete();
public void Complete ();
member this.Complete : unit -> unit
Public Sub Complete ()

Eccezioni

Questo metodo è stato già chiamato una volta.This method has already been called once.

Esempio

Nell'esempio seguente viene illustrato come utilizzare la TransactionScope classe per definire un blocco di codice per partecipare a una transazione.The following example demonstrates how to use the TransactionScope class to define a block of code to participate in a transaction.

// This function takes arguments for 2 connection strings and commands to create a transaction 
// involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the 
// transaction is rolled back. To test this code, you can connect to two different databases 
// on the same server by altering the connection string, or to another 3rd party RDBMS by 
// altering the code in the connection2 code block.
static public int CreateTransactionScope(
    string connectString1, string connectString2,
    string commandText1, string commandText2)
{
    // Initialize the return value to zero and create a StringWriter to display results.
    int returnValue = 0;
    System.IO.StringWriter writer = new System.IO.StringWriter();

    try
    {
        // Create the TransactionScope to execute the commands, guaranteeing
        // that both commands can commit or roll back as a single unit of work.
        using (TransactionScope scope = new TransactionScope())
        {
            using (SqlConnection connection1 = new SqlConnection(connectString1))
            {
                // Opening the connection automatically enlists it in the 
                // TransactionScope as a lightweight transaction.
                connection1.Open();

                // Create the SqlCommand object and execute the first command.
                SqlCommand command1 = new SqlCommand(commandText1, connection1);
                returnValue = command1.ExecuteNonQuery();
                writer.WriteLine("Rows to be affected by command1: {0}", returnValue);

                // If you get here, this means that command1 succeeded. By nesting
                // the using block for connection2 inside that of connection1, you
                // conserve server and network resources as connection2 is opened
                // only when there is a chance that the transaction can commit.   
                using (SqlConnection connection2 = new SqlConnection(connectString2))
                {
                    // The transaction is escalated to a full distributed
                    // transaction when connection2 is opened.
                    connection2.Open();

                    // Execute the second command in the second database.
                    returnValue = 0;
                    SqlCommand command2 = new SqlCommand(commandText2, connection2);
                    returnValue = command2.ExecuteNonQuery();
                    writer.WriteLine("Rows to be affected by command2: {0}", returnValue);
                }
            }

            // The Complete method commits the transaction. If an exception has been thrown,
            // Complete is not  called and the transaction is rolled back.
            scope.Complete();
        }
    }
    catch (TransactionAbortedException ex)
    {
        writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message);
    }

    // Display messages.
    Console.WriteLine(writer.ToString());

    return returnValue;
}
'  This function takes arguments for 2 connection strings and commands to create a transaction 
'  involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the 
'  transaction is rolled back. To test this code, you can connect to two different databases 
'  on the same server by altering the connection string, or to another 3rd party RDBMS  
'  by altering the code in the connection2 code block.
Public Function CreateTransactionScope( _
  ByVal connectString1 As String, ByVal connectString2 As String, _
  ByVal commandText1 As String, ByVal commandText2 As String) As Integer

    ' Initialize the return value to zero and create a StringWriter to display results.
    Dim returnValue As Integer = 0
    Dim writer As System.IO.StringWriter = New System.IO.StringWriter

    Try
    ' Create the TransactionScope to execute the commands, guaranteeing
    '  that both commands can commit or roll back as a single unit of work.
        Using scope As New TransactionScope()
            Using connection1 As New SqlConnection(connectString1)
                ' Opening the connection automatically enlists it in the 
                ' TransactionScope as a lightweight transaction.
                connection1.Open()

                ' Create the SqlCommand object and execute the first command.
                Dim command1 As SqlCommand = New SqlCommand(commandText1, connection1)
                returnValue = command1.ExecuteNonQuery()
                writer.WriteLine("Rows to be affected by command1: {0}", returnValue)

                ' If you get here, this means that command1 succeeded. By nesting
                ' the using block for connection2 inside that of connection1, you
                ' conserve server and network resources as connection2 is opened
                ' only when there is a chance that the transaction can commit.   
                Using connection2 As New SqlConnection(connectString2)
                    ' The transaction is escalated to a full distributed
                    ' transaction when connection2 is opened.
                    connection2.Open()

                    ' Execute the second command in the second database.
                    returnValue = 0
                    Dim command2 As SqlCommand = New SqlCommand(commandText2, connection2)
                    returnValue = command2.ExecuteNonQuery()
                    writer.WriteLine("Rows to be affected by command2: {0}", returnValue)
                End Using
            End Using

        ' The Complete method commits the transaction. If an exception has been thrown,
        ' Complete is called and the transaction is rolled back.
        scope.Complete()
        End Using
    Catch ex As TransactionAbortedException
        writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message)
    End Try

    ' Display messages.
    Console.WriteLine(writer.ToString())

    Return returnValue
End Function

Commenti

Quando si è soddisfatti che tutte le operazioni all'interno dell'ambito siano state completate correttamente, è consigliabile chiamare questo metodo solo una volta per indicare al gestore delle transazioni che lo stato tra tutte le risorse è coerente e che è possibile eseguire il commit della transazione.When you are satisfied that all operations within the scope are completed successfully, you should call this method only once to inform that transaction manager that the state across all resources is consistent, and the transaction can be committed. È consigliabile inserire la chiamata come ultima istruzione nel using blocco.It is very good practice to put the call as the last statement in the using block.

Per ulteriori informazioni sull'utilizzo di questo metodo, vedere l'argomento implementazione di una transazione implicita mediante ambito di transazione .For more information on how this method is used, see the Implementing An Implicit Transaction Using Transaction Scope topic.

La mancata chiamata di questo metodo interrompe la transazione, perché la gestione transazioni lo interpreta come un errore di sistema o le eccezioni generate nell'ambito della transazione.Failing to call this method aborts the transaction, because the transaction manager interprets this as a system failure, or exceptions thrown within the scope of transaction. Tuttavia, si noti anche che la chiamata a questo metodo non garantisce un commit della transazione.However, you should also note that calling this method does not guarantee a commit of the transaction. Si tratta semplicemente di un modo per passare alla gestione transazioni le informazioni sullo stato.It is merely a way of informing the transaction manager of your status. Dopo aver chiamato questo metodo, non è più possibile accedere alla transazione di ambiente tramite la Current proprietà e il tentativo di eseguire questa operazione comporta la generazione di un'eccezione.After calling this method, you can no longer access the ambient transaction via the Current property, and trying to do so results in an exception being thrown.

Il lavoro effettivo del commit tra il gestore delle risorse si verifica in corrispondenza dell' End Using istruzione se l' TransactionScope oggetto ha creato la transazione.The actual work of commit between the resources manager happens at the End Using statement if the TransactionScope object created the transaction. In caso contrario, il commit viene eseguito ogni volta che il metodo Commit viene chiamato dal proprietario dell'oggetto CommittableTransaction.If it did not create the transaction, the commit occurs whenever Commit is called by the owner of the CommittableTransaction object. A questo punto, il gestore delle transazioni chiama i gestori delle risorse e li informa di eseguire il commit o il rollback, a seconda che il metodo sia stato chiamato sull' TransactionScope oggetto.At that point the Transaction Manager calls the resource managers and informs them to either commit or rollback, based on whether this method was called on the TransactionScope object.

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