SQL依赖于基于Connections数量的更改事件触发的依赖关系

Question

我刚刚尝试实现sql依赖来检测表中的更改，只要实现我在表中更改数据时就会获得触发器，但问题是我根据连接数得到触发器。 例如，如果我在2个浏览器中打开了我的url，那么当表中发生更改时，对change事件的依赖会被触发两次，如果它被打开三次，那么我的on change事件将被触发很快三次。

这是我尝试的代码。

        private void GetUsers()
        {   
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand command = connection.CreateCommand())
                {
                    command.CommandType = CommandType.Text;
                    command.CommandText = "SELECT FirstName, LastName FROM dbo.[Users]";

                    command.Notification = null;

                    //  creates a new dependency for the SqlCommand
                    SqlDependency dependency = new SqlDependency(command);
                    //  creates an event handler for the notification of data
                    //      changes in the database.
                    //  NOTE: the following code uses the normal .Net capitalization methods, though
                    //      the forum software seems to change it to lowercase letters
                    dependency.OnChange += new OnChangeEventHandler(Dependency_OnChange);

                    connection.Open();

                    List<UserInfo> userList = new List<UserInfo>();
                    using (IDataReader userDataReader = command.ExecuteReader())
                    {
                        if (userDataReader != null)
                        {
                            while (userDataReader.Read())
                            {
                                UserInfo userInfo = new UserInfo();
                                userInfo.FirstName = Convert.IsDBNull(userDataReader["FirstName"]) ? string.Empty : Convert.ToString(userDataReader["FirstName"]);
                                userInfo.LastName = Convert.IsDBNull(userDataReader["LastName"]) ? string.Empty : Convert.ToString(userDataReader["LastName"]);
                                userList.Add(userInfo);
                            }
                        }
                    }

                    if (userList != null && userList.Count > 0)
                    {
                        this.dgUserList.DataSource = userList;
                        this.dgUserList.DataBind();
                    }
                }
            }
        }

private void Dependency_OnChange(object sender, SqlNotificationEventArgs e)
        {
            this.GetUsers();

            // this will remove the event handler since the dependency is only for a single notification
            SqlDependency dependency = sender as SqlDependency;

            //  NOTE: the following code uses the normal .Net capitalization methods, though
            //      the forum software seems to change it to lowercase letters
            dependency.OnChange -= new OnChangeEventHandler(Dependency_OnChange);


            // To broadcast my message
            ChatHub chat = new ChatHub();
            chat.send("myname", "New Registration Done");
        }

非常感谢任何帮助。