我需要通过try/catch包装TransactionScope吗？

Question

MSDN包含以下代码示例:

// 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);
    }
    catch (ApplicationException ex)
    {
        writer.WriteLine("ApplicationException Message: {0}", ex.Message);
    }

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

    return returnValue;
}

我不清楚:

• 我什么时候需要捕获TransactionAbortedException？
• 我目前正在应用程序生存期间存储与数据库的连接,而不是每次都打开和关闭它.这与使用交易有冲突吗？(或者这是一般的缺陷吗？)
• 如果我不关心值是否实际插入,我需要做什么？(我只是想确保数据库不会被破坏.)

Answer 1

不,TransactionScope不需要try/ catch,因为您应该已经使用它using,并且最后一步(根据示例)应该标记它已完成.如果它Dispose() 没有完成就会命中,那么它会回滚.

你的子弹:

• 你没有,除非你有一个非常具体的理由来处理这个例外; 我从来没有以特定的方式处理这种情况- 它是如此出乎意料,我很高兴它成为真正的特殊事件
• 存储你自己的开放连接在这里不是一个好主意 - 除了潜在的线程问题,并且有不必要的开放连接:你忽略了默认情况下已经内置连接池的事实(至少,使用SQL Server) .含义:您SqlConnection根据需要创建/打开一个新的(严格范围)并且池担心实际连接 - 您可能会在此处增加开销,但获得的收益很少(在池中找到现有连接非常快).如果你仔细检查,你可能会注意到,即使你Close()的连接,db-server报告它正在使用中; 那是因为你Close()只是把它放回池中重复使用
• 没什么; 交易应该是ACID