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May 12, 2013

Here I will explain how to show  or add multiple markers to Google maps V3 from database in website using JavaScript or JavaScript Show multiple markers in Google maps using database in


In previous article I explained clearly how to add Google map to website in, Add marker to Google map in website, JavaScript Add multiple markers to google map, jQuery image slideshow in, Sitemap navigation control example in and many articles relating to jQuery, JavaScript, Now I will explain how to add multiple markers to Google maps from database in website.

Before add multiple markers to Google map from database we need to get Google API key for that please check below url

Once you got the key create new table in your database like as shown below

Column Name
Data Type
Allow Nulls
int(set identity property=true)
Once table creation completed enter some sample data like as shown below

Now write the following code in your aspx to show multiple markers in Google map from database like as shown below 

<html xmlns="">
<title>Show/Add multiple markers to Google Maps from database in website</title>
<style type="text/css">
html { height: 100% }
body { height: 100%; margin: 0; padding: 0 }
#map_canvas { height: 100% }
<script type="text/javascript" src = "">
<script type="text/javascript">
function initialize() {
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);
for (i = 0; i < markers.length; i++) {
var data = markers[i]
var myLatlng = new google.maps.LatLng(, data.lng);
var marker = new google.maps.Marker({
position: myLatlng,
map: map,
title: data.title
(function(marker, data) {

// Attaching a click event to the current marker
google.maps.event.addListener(marker, "click", function(e) {
infoWindow.setContent(data.description);, marker);
})(marker, data);
<body onload="initialize()">
<form id="form1" runat="server">
<div id="map_canvas" style="width: 500px; height: 400px"></div>
If you observe above code in header section I mentioned multiple latitude and longitudes of different cities and by default I mentioned one city latitude and longitude by using that default details we can center the map to near place of other cities based on that other cities whatever we are going to mark are visible.

In remaining code markers are used to add marking in google map and infowindow is used to show info of all the cities based on the description whatever we mentioned in json string.

Now add following namespaces in code behind

 C# Code

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
After that write the following code in code behind

// This method is used to convert datatable to json string
public string ConvertDataTabletoString()
DataTable dt = new DataTable();
using (SqlConnection con = new SqlConnection("Data Source=SureshDasari;Initial Catalog=master;Integrated Security=true"))
using (SqlCommand cmd = new SqlCommand("select title=City,lat=latitude,lng=longitude,description from LocationDetails", con))
SqlDataAdapter da = new SqlDataAdapter(cmd);
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]);
return serializer.Serialize(rows);


Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlClient
Partial Class Default3
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
End Sub
' This method is used to convert datatable to json string
Public Function ConvertDataTabletoString() As String
Dim dt As New DataTable()
Using con As New SqlConnection("Data Source=SureshDasari;Initial Catalog=master;Integrated Security=true")
Using cmd As New SqlCommand("select title=City,lat=latitude,lng=longitude,description from LocationDetails", con)
Dim da As New SqlDataAdapter(cmd)
Dim serializer As New System.Web.Script.Serialization.JavaScriptSerializer()
Dim rows As New List(Of Dictionary(Of String, Object))()
Dim row As Dictionary(Of String, Object)
For Each dr As DataRow In dt.Rows
row = New Dictionary(Of String, Object)()
For Each col As DataColumn In dt.Columns
row.Add(col.ColumnName, dr(col))
Return serializer.Serialize(rows)
End Using
End Using
End Function
End Class


Download Sample Code Attached

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Anonymous said...

Nice article, Thanks :)


Anonymous said...

Hi suresh..
it shows the following error

Google has disabled use of the Maps API for this application. The provided key is not a valid Google API Key, or it is not authorized for the Google Maps Javascript API v3 on this site. If you are the owner of this application, you can learn about obtaining a valid key here:

in which way i can solve this

S PullaReddy said...

var markers = JSON.parse('<%=ConvertDataTabletoString() %>');

i am getting markers as undefined .is there any other way to parse it...

Anonymous said...


Anonymous said...

Very helpful.

manish arora said...

good sir ji

Anonymous said...

hi shows an JSON is not found ... what do i do?

Anonymous said...

Pls provide an article on updating marker on google map taking lat and long from database without reloading the map means only updating the marker positions asap............Shibham

Anonymous said...

Pls provide an article on updating marker on google map taking lat and long from database without reloading the map means only updating the marker positions asap

RAJ Patidar said...


Darpan Pathak said...

I have made it guys .... Contact me for the details ... i solved this issue "updating marker on google map taking lat and long from database without reloading the map means only updating the marker positions"

Anonymous said...

Thanks a lot.

aman said...

i wrote the same code but it is not displaying anything.please help

Muh Zuhry said...

my marker didn't show??? but when readeng table the procces is completed nothing error.... how can???

Nilesh Monde said...

my marker didnt show why ?

Nilesh Monde said...

Hi, i intialize google map intially then i write your javascipt code but marker not displaying.... i have two dropdownlist when i select from one dropdownlist that location should display on google map. how to achieve this

Nilesh Monde said...

i run your page in content page but not works

Anonymous said...

I case of master page there is no body tag then how can i call initialize function

Pravin Dukare said...

Hi Suresh,

Please give me a solution for,

Code is working nicely but It is not browser responsive .
when i set div id="map_canvas" style="width:100%; height: 400px"
and my page to resize when the browser resizes, but it's not working.
Please help for this..
Thank you.

Anonymous said...

Getting error "0x800a03f6 - JavaScript runtime error: Invalid character" if my database has more then 1 coordinates. please help

r.suresh kumar Mcc said...

thank you suresh anna..
escape great escape from my project manager.

R.suresh kumar chennai

Anonymous said...

getting error like this('<%=ConvertDataTabletoString()%>');,it says it is not decleared

Thank you

Sourabh Choubey said...

var markers = JSON.parse('<%=ConvertDataTabletoString() %>');
if (marker == null)
when i checked it i got that my markers will no any data help me

Sourabh Choubey said...

sorry for mistake i have data but when the page is load my map is not visible at all me....
var markers = JSON.parse('<%=ConvertDataTabletoString() %>');
if (markers == null)

Sourabh Choubey said...

thanks suresh i have completed what i have to do....

Anonymous said...

THANK YOU so much! I've been searching for an efficient way to do this for weeks.

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