Question

为catch子句中已存在的SqlTransaction RollBack实现错误处理的最佳方法是什么？我的代码大致如下：

using (SqlConnection objSqlConn = new SqlConnection(connStr)) {
  objSqlConn.Open();

  using (SqlTransaction objSqlTrans = objSqlConn.BeginTransaction()) {
    try {
      // code
      // more code
      // and more code
    }
    catch (Exception ex) {
      // What happens if RollBack() has an exception?
      objSqlTrans.Rollback();
      throw ex;
    }
  }
}

我相信我的应用程序在try块中有一个异常，后者又被catch块捕获，然后尝试了RollBack。但是，我看到的错误说明了SqlTransaction.ZombieCheck（），这让我想知道RollBack（）本身是否也引发了异常。那么，我需要在RollBack（）中实现某种类型的错误处理吗？我该怎么做并设法保持将执行放入catch块的异常？

编辑 - 我的所有代码：

using (SqlConnection objSqlConn = new SqlConnection(connStr)) {

    objSqlConn.Open();

    // Begin Transaction
    using (SqlTransaction objSqlTrans = objSqlConn.BeginTransaction()) {

        try {
            // Create file in db (which in turn creates it on disk according to where the 
            // ...FileStream points)
            SqlCommand objSqlCmd = new SqlCommand("usp_FileAdd", objSqlConn, objSqlTrans);
            objSqlCmd.CommandType = CommandType.StoredProcedure;

            // Sql parameter - report name
            SqlParameter objSqlParam1 = new SqlParameter("@ObjectID", SqlDbType.Int);
            objSqlParam1.Value = objID;

            // Sql out parameter - returns the file path
            SqlParameter objSqlParamOutput = new SqlParameter("@filepath", SqlDbType.VarChar, -1);
            objSqlParamOutput.Direction = ParameterDirection.Output;

            // Add Sql parameters to command obj
            objSqlCmd.Parameters.Add(objSqlParam1);
            objSqlCmd.Parameters.Add(objSqlParamOutput);

            // Execute command object
            objSqlCmd.ExecuteNonQuery();

            // Path to the FileStream
            string path = objSqlCmd.Parameters["@filepath"].Value.ToString();

            // Reset command object to get FileStream
            objSqlCmd = new SqlCommand(
                "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()",
                objSqlConn,
                objSqlTrans);

            // Execute command object
            Object obj = objSqlCmd.ExecuteScalar();

            if (obj != DBNull.Value) {
                // Byte array representing the FileStream
                byte[] fsBytes = (byte[])obj;

                SqlFileStream sqlFS = new SqlFileStream(path, fsBytes, FileAccess.Write);

                using (FileStream fs = fi.OpenRead()) {
                    //byte[] b = new byte[1024];
                    byte[] b = new byte[4096];
                    int read;

                    fs.Seek(0, SeekOrigin.Begin);

                    while ((read = fs.Read(b, 0, b.Length)) > 0) {
                        sqlFS.Write(b, 0, read);
                    }
                }

                sqlFS.Close();
            }

            // Commit the transaction
            objSqlTrans.Commit();
        }
        catch (Exception ex) {
            objSqlTrans.Rollback();
            throw ex;
        }
    }
}

Answer 1

这个片段应如下所示：

using (SqlConnection objSqlConn = new SqlConnection(connStr)) {
 objSqlConn.Open();

 using (SqlTransaction objSqlTrans = objSqlConn.BeginTransaction()) {
   try {
     // code
     // more code
     // and more code
   }
   catch (Exception ex) {
     // What happens if RollBack() has an exception?
     try {
        objSqlTrans.Rollback();
     } catch (Exception ex2) {
        /* can't roll back -- db gone? db will do it for us since we didn't commit. */
     }
     throw;
   }
 }
}

编辑：想想看，在这种特殊情况下根本不需要整个try / catch，因为用未提交的事务关闭连接会回滚事务，所以块看起来像这样：

using (SqlConnection objSqlConn = new SqlConnection(connStr)) {
 objSqlConn.Open();

 using (SqlTransaction objSqlTrans = objSqlConn.BeginTransaction()) {
  // code
  // more code
  // and more code
 }
}

Answer 2

你已经有了

using (SqlTransaction objSqlTrans = objSqlConn.BeginTransaction())

如果尚未提交，则当使用块结束时，这将导致事务回滚。

所以我会完全删除catch块。

至于回滚失败时会发生什么，我首先要认识到这是一个非常糟糕的情况，并遵循Eric Lippert关于类似问题的建议。 here

如何在RollBack上捕获异常

2 个答案: