单个SqlConnection具有Transaction,多个命令的情况

Question

我试图只使用一个连接并一起运行两个命令,一个使用事务,一个不使用.

没有跟踪/日志记录功能,因为此解决方案部署在另一个位置.因此,当流程部分失败时,我至少可以按照日志进行操作.

我将在这里添加我的测试代码:

SqlConnection connection = GetConnection();
SqlTransaction transaction = null;

try
{
    connection.Open();
    transaction = connection.BeginTransaction();

    SqlCommand logCommand = new SqlCommand("Log before main command", connection);
    logCommand.ExecuteNonQuery();

    string sql = "SELECT 1";
    SqlCommand command = new SqlCommand(sql, connection, transaction);
    int rows = command.ExecuteNonQuery();

    logCommand = new SqlCommand("Log after main command", connection);
    logCommand.ExecuteNonQuery();

    // Other similar code

    transaction.Commit();
    command.Dispose();
}
catch { /* Rollback etc */ }
finally { /* etc */ }

我收到一个错误:

当分配给命令的连接处于挂起的本地事务中时,ExecuteNonQuery要求命令具有事务.该命令的Transaction属性尚未初始化.

如果没有其他无交易连接,有没有办法实现我想要做的事情？

或者,如果有一个更好的建议,以不同的方式通过单个连接优化我的代码,我就可以开始学习它.

Answer 1

错误发生在这里：

SqlConnection connection = GetConnection();
SqlTransaction transaction = null;

try
{
    connection.Open();
    transaction = connection.BeginTransaction();

    SqlCommand logCommand = new SqlCommand("Log before main command", connection); // <--- did not give the transaction to the command
    logCommand.ExecuteNonQuery(); // <--- Exception: ExecuteNonQuery requires the command to have a transaction ...

    string sql = "SELECT 1";
    SqlCommand command = new SqlCommand(sql, connection, transaction);
    int rows = command.ExecuteNonQuery();

    logCommand = new SqlCommand("Log after main command", connection);
    logCommand.ExecuteNonQuery(); // <--- Same error also would have happened here

    // Other similar code

    transaction.Commit();
    command.Dispose();
}
catch { /* Rollback etc */ }
finally { /* etc */ }

发生这种情况的原因是，当连接在事务中登记时，该连接上的所有命令都在该事务中。换句话说，您不能让命令“选择退出”事务，因为事务适用于整个连接。

不幸的是，SqlClient API 有点误导，因为在调用 connection.BeginTransaction() 之后，您仍然必须将 SqlTransaction 提供给 SqlCommand。如果您没有显式地将事务交给命令，那么当您执行该命令时，SqlClient 会为此责备您（“不要忘记告诉我有关我已经知道我所在的事务的信息！”）这是你看到的例外。

这种笨拙是一些人更喜欢使用 TransactionScope 的原因之一，尽管我个人不喜欢将 TransactionScope 用于非分布式事务，因为它的“隐式魔法”API 以及与异步的不良交互。

如果您不希望“log”命令与主命令位于同一事务中，则必须为它们使用另一个连接，或者仅在该主命令的持续时间内保留事务：

try
{
    connection.Open();

    // No transaction
    SqlCommand logCommand = new SqlCommand("select 'Log before main command'", connection);
    logCommand.ExecuteNonQuery();

    // Now create the transaction
    transaction = connection.BeginTransaction();
    string sql = "SELECT 1";
    SqlCommand command = new SqlCommand(sql, connection, transaction);
    int rows = command.ExecuteNonQuery();
    transaction.Commit();

    // Transaction is completed, now there is no transaction again
    logCommand = new SqlCommand("select 'Log after main command'", connection);
    logCommand.ExecuteNonQuery();

    // Other similar code

    command.Dispose();
}
//catch { /* Rollback etc */ }
finally
{
    if (transaction != null)
    {
        transaction.Dispose();
    }
}

如果您确实希望他们成为交易的一部分，则必须明确地将交易交给他们：

SqlConnection connection = GetConnection();
SqlTransaction transaction = null;

try
{
    connection.Open();
    transaction = connection.BeginTransaction();

    SqlCommand logCommand = new SqlCommand("select 'Log before main command'", connection, /* here */ transaction);
    logCommand.ExecuteNonQuery();

    string sql = "SELECT 1";
    SqlCommand command = new SqlCommand(sql, connection, transaction);
    int rows = command.ExecuteNonQuery();

    logCommand = new SqlCommand("select 'Log after main command'", connection, /* and here */ transaction);
    logCommand.ExecuteNonQuery();

    // Other similar code

    transaction.Commit();
    command.Dispose();
}
//catch { /* Rollback etc */ }
finally
{
    if (transaction != null)
    {
        transaction.Dispose();
    }
}