SqlDependency OnChange事件多次触发

我有一个项目的评论系统,你可以查看不同的页面,他们有自己的评论。我正在尝试使用带有SqlDependency的信号器来自动在页面上提取新注释。 我的问题是,如果多人打开了与SqlDependency的连接,则从sqlnotification调用的“onchange”事件的数量开始成倍增加。每个用户都会多次调用onchange,而不是只调用一次。(即使他们没有查看相同的评论页面)

    private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
    {
        SqlDependency dependency = (SqlDependency)sender;
        dependency.OnChange -= new OnChangeEventHandler(dependency_OnChange);

        if (e.Info.ToString().ToLower().Trim() == "insert")
        {
            MyHub.Show();
        }
    }

这对我来说似乎没有任何改变,所以我不知道最好的预防方法是什么。

GetData方法:

    [WebMethod]
    public IEnumerable<DUpdates> GetData(string dnum, string date)
    {
        if (Common.IsValidInt32(dnum)) //just a function that check for valid int
        {
            using (var connection =
                new SqlConnection(ConfigurationManager.ConnectionStrings["SConnectionString"].ConnectionString))
            {

                connection.Open();

            using (SqlCommand command = new SqlCommand(@"SELECT [Comment] FROM dbo.DUpdates WHERE (DID = " + dnum + ") AND (Deleted = 0) AND CreateDate > @Date ORDER BY CreateDate DESC", connection))
            {
                command.Parameters.Add("@Date", SqlDbType.DateTime);
                command.Parameters["@Date"].Value = date;

                command.Notification = null;

                SqlDependency dependency = new SqlDependency(command);

                dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);


                if (connection.State == ConnectionState.Closed)
                    connection.Open();

                using (var reader = command.ExecuteReader())
                {
                    return reader.Cast<IDataRecord>().Select(x => new DUpdates()
                    {
                        comment = x.GetString(0)
                    }).ToList();
                }
            }
        }
    }

JS资料:

    $(function() {
        var job = $.connection.myHub;

        job.client.displayStatus = function () {
            getData();
        };

        $.connection.hub.start();
        getData();
    });

    function getData() {
        var params = (new URL(document.location)).searchParams;
        var id = params.get("id");
        var dt = $("#accessdate").val();

        $.ajax({
            url: 'dupdatesservice.asmx/GetData',
            data: JSON.stringify({dnum: id, date: dt}),
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            type: "POST",
            success: function (data) {
                if (data.d.length > 0) {
                    $("#testdiv").prepend(data.d[0].comment);
                }
            }
        });
    }