While displaying data in the google map you have scenarios where you want to do it in the customized manner.

  public string ConvertDataTabletoString()
    {
        DataTable dt = new DataTable();
        using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnectionString"].ConnectionString))
        {
            using (SqlCommand cmd = new SqlCommand("select title=Company,lat=latitude,lng=longitude,image from MapDimension", con))
            {
                con.Open();
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);
                System.Web.Script.Serialization.JavaScriptSerializer serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
                List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
                Dictionary<string, object> row;
                foreach (DataRow dr in dt.Rows)
                {
                    row = new Dictionary<string, object>();
                    foreach (DataColumn col in dt.Columns)
                    {
                        row.Add(col.ColumnName, dr[col]);
                    }
                    rows.Add(row);
                }
                return serializer.Serialize(rows);
            }
        }

So for this you need to fetch or get the values form the datasource and fill into the map API.

        var markers = JSON.parse('<%=ConvertDataTabletoString() %>');
        var mapOptions = {
        center: new google.maps.LatLng(markers[0].lat, markers[0].lng),
zoom: 5,
mapTypeId: google.maps.MapTypeId.ROADMAP
//  marker:true
};
var infoWindow = new google.maps.InfoWindow();
var map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
var image;
for (i = 0; i < markers.length; i++) {
var data = markers[i]
var myLatlng = new google.maps.LatLng(data.lat, data.lng);

var contentString = '<div id="content" style="margin-left:15px; margin-top:3px;overflow:hidden;">' +
'<div id="bodyContent">' + '<img src=' + data.image + ' style="width:172px;height:45px;"  alt="WebStreet.in"/>' + '<br><font style="color:darkblue;font:11px tahoma;margin-left:5px;">' + data.title + ' Your Trusted IT Solutions Provider</font>' +
'</div>' +
'</div>';

Here we have get the data from the datasource and filled it with the google map API map window according to our need.