TransactionScope.Dispose 方法

定義

結束交易範圍。Ends the transaction scope.

public:
 virtual void Dispose();
public void Dispose ();
abstract member Dispose : unit -> unit
override this.Dispose : unit -> unit
Public Sub Dispose ()

實作

範例

下列範例示範如何使用TransactionScope類別來定義要參與交易的程式碼區塊。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

備註

呼叫這個方法會標記交易範圍的結尾。Calling this method marks the end of the transaction scope. 如果物件已建立交易並Complete TransactionScope在範圍上呼叫,物件會在呼叫這個方法時,嘗試認可交易。 TransactionScopeIf the TransactionScope object created the transaction and Complete was called on the scope, the TransactionScope object attempts to commit the transaction when this method is called. 在此情況下,這個方法會封鎖,直到交易處理的第一個階段完成為止。In this case, this method blocks until the first phase of transaction processing is complete. 第一個階段會在交易中的所有資源管理員和登記對交易結果投票,而且TransactionManager已永久決定認可或中止交易之後結束。The first phase ends after all resource managers and enlistments in the transaction have voted on the transaction outcome and the TransactionManager has durably decided to commit or abort the transaction. 處理的第二個階段一律是非同步。The second phase of processing is always asynchronous. 因此,不保證只有從給定交易內認可的資料,之後就會立即可供使用,而不會在不使用另一筆交易來查看此資料時立即使用。Therefore, there is no guarantee that data just committed from within a given transaction will be immediately available afterwards when not using another transaction to view this data.

C# 使用using結構可確保即使發生例外狀況,也會呼叫這個方法。The use of the C# using construction ensures that this method is called even if an exception occurs. 在呼叫這個方法後發生的例外狀況不太可能會影響異動。Exceptions that occur after calling this method may not affect the transaction. 這個方法也會將環境交易還原到其原始狀態。This method also restores the ambient transaction to it original state. 若未實際認可交易,則會擲回。TransactionAbortedExceptionA TransactionAbortedException is thrown if the transaction is not actually committed.

因為此方法會封鎖到交易處理的第一個階段完成,所以在 Windows Form (WinForm)應用程式中使用這個方法時,您應該非常小心,否則可能會發生鎖死。Because this method blocks until the first phase of transaction processing is complete, you should be extremely careful when using this method in a Windows Form (WinForm) application, or a deadlock can occur. 如果您在一個 WinForm 控制項事件內呼叫這個方法(例如,按一下按鈕),然後使用同步Invoke方法來指示控制項在處理交易的過程中執行某些 UI 工作(例如,變更色彩),將會發生鎖死。If you call this method inside one WinForm Control event (for example, clicking a button), and use the synchronous Invoke method to direct the control to perform some UI tasks (for example, changing colors) in the middle of processing the transaction, a deadlock will happen. 這是因為方法Invoke是同步的,而且會封鎖背景工作執行緒,直到 UI 執行緒完成其作業為止。This is because the Invoke method is synchronous and blocks the worker thread until the UI thread finishes its job. 不過,在我們的案例中,UI 執行緒也會等候工作者執行緒認可交易。However, in our scenario, the UI thread is also waiting for the worker thread to commit the transaction. 結果是,none 可以繼續進行,而範圍則會無限期等候認可完成。The result is that none is able to proceed and the scope waits indefinitely for the Commit to finish. 您應該使用BeginInvokeInvoke而不是任何可能的,因為它是非同步,因此較不容易發生鎖死。You should use BeginInvoke rather than Invoke wherever possible, because it is asynchronous and thus less prone to deadlock.

如需如何使用此方法的詳細資訊,請參閱使用交易範圍來執行隱含交易主題。For more information on how this method is used, see the Implementing An Implicit Transaction Using Transaction Scope topic.

適用於

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