C＃中的最佳做法的错误处理和传递错误信息

我使用asp.net和我一直在挣扎了简洁的方式来处理错误，如果有任何，到errormessage的传递给用户。例如，我有一个User类，类的UserManager和数据库类。 IMAGINA我想告诉所有的用户，显示我调用该方法GetAllUsers从UserManagerwhich返回用户对象的列表。此方法创建一个数据库对象，并调用方法的executeQuery（查询字符串）。

I am using asp.net and I am always struggling for a neat way to handle errors and if there are any, to pass the errormessage to the user. For example, I have an User class, UserManager class and a Database class. Imagina I want to show all the users, show I call the method GetAllUsers from UserManagerwhich returns a list of User objects. This method creates a Database object and calls the method ExecuteQuery(string query).

编辑：
现在我的问题，想象不顺心的事中的executeQuery（）方法（无法打开数据库）。我想通知打开数据库连接时，用户成才了问题。我应该如何做到这一点，处理这一个整洁的方式？

And now my issue, imagine something goes wrong in the ExecuteQuery() method (failed to open database). I want to notify the user someting went wrong when opening the database connection. How should I do this and handle this a neat way?

编辑2：

你会做这样的事情？或以其他方式？

Would you do it something like this? Or otherwise?

public class Database()
{
   private string _Error;

   // property error (only get)

   private void Open()
   {
     try
     {
       // Open DB
       // Fails because of error          
     }
     catch(Exception ex)
     {
       _Error = ex.Message;
     }
   }

   public DataSet ExecuteQuery(string query)
   {
      try
      {
        Open();

        // Execute query

        // return dataset
       }
       catch(Exception ex)
       {
          _Error = ex.Message;
          return null;
       }
   }
}

public class UserManager ()
{
   private string _Error;

   // Get property for Error       

   public List<User> GetAllUsers ()
   {
      Database db = new Database()

      Dataset DS = db.ExecuteQuery("my query goes here");

      (if DS == null)
      {
        _Error = db.Error;
        return null;
      }

   }
}

在上单击事件的用户界面：

In user interface on a click event:

protected void onClick_event(args)
{

  Usermanager userman = new UserManager();
  List<User> users = userman.GetAllUsers();

  if(users == null)
  {
    // make a error panel visible
    pnlError.Visible = true;
    lblError.Text = userman.Error
  }
}

这是一个很好的方法？