TransactionScope Klass

Definition

public ref class TransactionScope sealed : IDisposable

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public sealed class TransactionScope : IDisposable

public sealed class TransactionScope : IDisposable

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
type TransactionScope = class
    interface IDisposable

type TransactionScope = class
    interface IDisposable

Public NotInheritable Class TransactionScope
Implements IDisposable

Arv

Object

TransactionScope

Attribut

UnsupportedOSPlatformAttribute

Implementeringar

IDisposable

Exempel

I följande exempel visas hur du använder TransactionScope klassen för att definiera ett kodblock för att delta i en transaktion.

// 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

Kommentarer

Infrastrukturen System.Transactions tillhandahåller både en explicit programmeringsmodell baserad på Transaction klassen, samt en implicit programmeringsmodell med hjälp av TransactionScope klassen, där transaktioner hanteras automatiskt av infrastrukturen.

När du instansierar en TransactionScope av -instruktionen new avgör transaktionshanteraren vilken transaktion som ska ingå. När detta omfång fastställts deltar det alltid i den transaktionen. Beslutet baseras på två faktorer: om det finns en omgivande transaktion och värdet för parametern TransactionScopeOption i konstruktorn. Den omgivande transaktionen är den transaktion som koden körs i. Du kan hämta en referens till den omgivande transaktionen genom att anropa klassens Transaction.Current statiska Transaction egenskap. Mer information om hur den här parametern används finns i avsnittet "Transaktionsflödeshantering" i avsnittet Implementera en implicit transaktion med transaktionsomfång .

Om inget undantag inträffar inom transaktionsomfånget (dvs. mellan initieringen av TransactionScope objektet och anropet av dess Dispose metod) tillåts transaktionen där omfånget deltar fortsätta. Om ett undantag inträffar inom transaktionsomfånget återställs den transaktion som den deltar i.

När programmet har slutfört allt arbete som det vill utföra i en transaktion bör du bara anropa Complete metoden en gång för att informera transaktionshanteraren om att det är acceptabelt att genomföra transaktionen. Om du inte anropar den här metoden avbryts transaktionen.

Ett anrop till Dispose metoden markerar slutet på transaktionsomfånget. Undantag som inträffar efter att den här metoden anropats kanske inte påverkar transaktionen.

Om du ändrar värdet Current för inuti ett omfång genereras ett undantag när Dispose anropas. Men i slutet av omfånget återställs det tidigare värdet. Om du anropar DisposeCurrent i ett transaktionsomfång som skapade transaktionen avbryts transaktionen i slutet av omfånget.

Trådsäkerhet

Den här typen är trådsäker.

Se även

• Implementera en implicit transaktion med transaktionsomfång