Open PopUp reminder Daily when Database Date match with System DateTime using C# and jQuery in ASP.Net

Hi itsjayshah,

I have created a sample which full fill your requirement you need to modify the according to your need.

HTML

<div>
    <asp:ScriptManager ID="ScriptManager1" runat="server" />
    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            <br />
            <br />
            <asp:Label ID="lblDismissed" ForeColor="Green" Font-Bold="true" Font-Italic="true"
                runat="server" />
            <asp:Timer ID="tmAppointmentTimer" Interval="5000" runat="server" OnTick="CheckAppointment">
            </asp:Timer>
            <div class="modal" id="myModal" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
                <div class="modal-dialog">
                    <div class="modal-content">
                        <div class="modal-header">
                            <h4 class="modal-title">
                                Event Details
                            </h4>
                        </div>
                        <div class="modal-body">
                            <div class="row">
                                <div class="caption">
                                    EventName:- <b>
                                        <asp:Label ID="lblEventName" runat="server"></asp:Label></b>
                                    <br />
                                    EventDescription:- <b>
                                        <asp:Label ID="lblEventDescription" runat="server" /></b>
                                </div>
                            </div>
                        </div>
                        <div class="modal-footer">
                            <asp:Button ID="Button1" Text="Dismiss" OnClick="Dismiss" class="btn btn-info" runat="server" />
                        </div>
                    </div>
                </div>
            </div>
            <div>
                <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
                <script type="text/javascript" src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
                <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
                <script type="text/javascript">
                    function CloseAppointMent() {
                        $('[id*=myModal]').modal('hide');
                        $("[class*='modal-backdrop in']").remove();
                    }
                </script>
            </div>
        </ContentTemplate>
    </asp:UpdatePanel>
</div>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        lblDismissed.Text = "Checking whether any event present or not.";
    }
}

protected void Dismiss(object sender, EventArgs e)
{
    if (ViewState["Data"] != null)
    {
        DataTable dt = ViewState["Data"] as DataTable;
        int index = new System.Data.DataView(dt).ToTable(false, new[] { "EventName" })
            .AsEnumerable()
            .Select(row => row.Field<string>("EventName"))
            .ToList()
            .FindIndex(col => col == lblEventName.Text);
        dt.Rows[index]["Status"] = "Dismissed";
        dt.AcceptChanges();
        ViewState["Data"] = dt;
        lblDismissed.Text = "You have Dismissed the Event";
        string script = "function pageLoad(sender, args) { if (args.get_isPartialLoad()) {CloseAppointMent(); }}";
        ScriptManager.RegisterStartupScript(this, GetType(), "AppointMent", script, true);
    }
}

protected void CheckAppointment(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt.Columns.Add("EventName");
    dt.Columns.Add("EventDescription");
    dt.Columns.Add("EventDate");
    dt.Rows.Add("EventName 1", "EventDescription 1", "3/28/2017");
    dt.Rows.Add("EventName 2", "EventDescription 2", "3/10/2017");
    dt.Rows.Add("EventName 3", "EventDescription 3", "3/12/2017");
    dt.Rows.Add("EventName 4", "EventDescription 4", "3/9/2017");
    dt.Rows.Add("EventName 5", "EventDescription 5", "3/6/2017");
    dt.Columns.Add("Status");
    if (ViewState["Data"] == null)
    {
        ViewState["Data"] = dt;
    }
    else
    {
        dt = ViewState["Data"] as DataTable;
    }
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        string datetime = DateTime.Now.ToShortDateString();

        if (datetime == dt.Rows[i]["EventDate"].ToString() && dt.Rows[i]["Status"].ToString() != "Dismissed")
        {
            lblEventName.Text = dt.Rows[i]["EventName"].ToString();
            lblEventDescription.Text = dt.Rows[i]["EventDescription"].ToString();
            string script = "function pageLoad(sender, args) { if (args.get_isPartialLoad()) {$('[id*=myModal]').modal('show'); }}";
            ScriptManager.RegisterStartupScript(this, GetType(), "AppointMent", script, true);
            break;
        }
    }
}

Screenshot