multiple markers on gmap.net

Question

Hi I have 1000 latitudes , longitudes and want to display all of them on maps . I tried several ways to do it but not luck.....I have a datagridview which has client,lat,long,region. each client has a region.I have a combobox when I click on combobox region 1 it should display all clients on region 1 on map can it be possible. please help.

if (comboBox5.SelectedIndex == 0)//(REGION 1)
{
    String Query = " SELECT top  Latitude,Longitude  FROM[ICPS].[dbo].[Sheet3_kir]   ";
    SqlCommand cmdDatabase = new SqlCommand(Query, conDatabase);
    SqlDataReader myReader;
    gMapControl1.MapProvider = GMap.NET.MapProviders.BingMapProvider.Instance;
    GMap.NET.GMaps.Instance.Mode = GMap.NET.AccessMode.ServerOnly;

    GMapOverlay markersOverlay = new GMapOverlay("VCS MAP");
    //gMapControl1.Overlays.Add(markersOverlay); 

    for (int i = 0; i <= dataGridView1.Rows.Count; i++)
    {
        foreach (DataGridViewRow row in dataGridView1.Rows)
        {
            var Latitude = double.Parse(dataGridView1.Columns[1].ToString());
            var Longitude = double.Parse(dataGridView1.Columns[2].ToString());
            gMapControl1.Position = new PointLatLng(Latitude, Longitude);
            // GMarkerGoogle marker = new GMarkerGoogle(new PointLatLng(float.Parse(this.dataGridView1.Columns[1].ToString), float.Parse(this.textBox26.Text)),
            // GMarkerGoogleType.green);
            GMarkerGoogle m = new GMarkerGoogle(gMapControl1.Position, GMarkerGoogleType.green_pushpin);
            //markersOverlay.Markers.Add(m);
        }
    }

Answer 1

            MySqlDataAdapter da = new MySqlDataAdapter("select * from sinkhole where sinkhole_status = '" + "Active" + "'", Conn);
            MySqlCommandBuilder cBuilder = new MySqlCommandBuilder(da);

            DataTable dataTable = new DataTable();
            DataSet ds = new DataSet();
            da.Fill(dataTable);

            for (int i = dataTable.Rows.Count - 1; i >= 0; i--)
            {
                double lng = double.Parse(dataTable.Rows[i][4].ToString());
                double lat = double.Parse(dataTable.Rows[i][3].ToString());
                string location = dataTable.Rows[i][2].ToString();
                string name = dataTable.Rows[i][1].ToString();
                string desciption = dataTable.Rows[i][5].ToString();

                GMapOverlay markersOverlay = new GMapOverlay(map, "marker");
                GMapMarkerGoogleGreen marker = new GMapMarkerGoogleGreen(new PointLatLng(lat, lng));
                markersOverlay.Markers.Add(marker);
                //marker.ToolTipMode = MarkerTooltipMode.Always;
                marker.ToolTip = new GMapRoundedToolTip(marker);
                marker.ToolTipText = "Coordinates: (" + Convert.ToString(lat) + "," + Convert.ToString(lng) + ")" + "\nLocation: " + location + "\nName: " + name;
                map.Overlays.Add(markersOverlay);