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TransactionScope.Complete Method

Indicates that all operations within the scope are completed successfully.

Namespace: System.Transactions
Assembly: System.Transactions (in system.transactions.dll)

public void Complete ()
public void Complete ()
public function Complete ()
Not applicable.

Exception typeCondition

InvalidOperationException

This method has already been called once.

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. It is very good practice to put the call as the last statement in the using block.

For more information on how this method is used, see the Implement Implicit Transactions using Transaction Scope topic.

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. However, you should also note that calling this method does not guarantee a commit of the transaction. It is merely a way of informing the transaction manager of your status. 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.

The actual work of commit between the resources manager happens at the End Using statement if the TransactionScope object created the transaction. If it did not create the transaction, the commit occurs whenever Commit is called by the owner of the CommittableTransaction object. 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.

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();

    // 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))
        {
            try
            {
                // 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))
                    try
                    {
                        // 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);
                    }
                    catch (Exception ex)
                    {
                        // Display information that command2 failed.
                        writer.WriteLine("returnValue for command2: {0}", returnValue);
                        writer.WriteLine("Exception Message2: {0}", ex.Message);
                    }
            }
            catch (Exception ex)
            {
                // Display information that command1 failed.
                writer.WriteLine("returnValue for command1: {0}", returnValue);
                writer.WriteLine("Exception Message1: {0}", ex.Message);
            }
        }

        // The Complete method commits the transaction. If an exception has been thrown,
        // Complete is not  called and the transaction is rolled back.
        scope.Complete();
    }

    // The returnValue is greater than 0 if the transaction committed.
    if (returnValue > 0)
    {
        writer.WriteLine("Transaction was committed.");
    }
    else
    {
        // You could write additional business logic here, for example, you can notify the caller 
        // by throwing a TransactionAbortedException, or logging the failure.
        writer.WriteLine("Transaction rolled back.");
    }

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

    return returnValue;
}

Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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