Demo:-
Instruction:- To Execute this code first of all make three table in a Database.which are are connected to each other with unique id.Simply make three tables like this..
CountryTable
StateTable
CityTable
And now these are design & code Behind Paste this code in your file
Design Code:-
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CountryDropdowns.aspx.cs" Inherits="CountryDropdowns" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>CasCading Dropdowns Sample</title>
<style type="text/css">
.style1
{
height: 30px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<table align="center" cellpadding="10px" cellspacing="5" style="background:skyblue;width:400px;border:solid 2px darkred;padding:8px;">
<tr>
<td colspan="2" valign="bottom" class="style1">
<h3>Drop Down Menu Attached With Selection Of One Another</h3> <hr />
</td>
</tr>
<tr>
<td>
Select Country:
</td>
<td>
<asp:DropDownList ID="ddlCountry" runat="server" AutoPostBack="true"
onselectedindexchanged="ddlCountry_SelectedIndexChanged" Height="16px"
Width="119px"></asp:DropDownList>
</td>
</tr>
<tr>
<td>
Select State:
</td>
<td>
<asp:DropDownList ID="ddlState" runat="server" AutoPostBack="true"
onselectedindexchanged="ddlState_SelectedIndexChanged" Height="18px" Width="122px"></asp:DropDownList>
</td>
</tr>
<tr>
<td>
Select City:
</td>
<td>
<asp:DropDownList ID="ddlRegion" runat="server" Height="19px" Width="125px"></asp:DropDownList>
</td>
</tr>
<tr><td></td><td style="font-size:small" align="right">R.Upadhyay</td></tr>
</table>
</div>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
public partial class CountryDropdowns : System.Web.UI.Page
{
private String strConnection = "Data Source=IT-HP\\sqlexpress;Initial Catalog=Employee;Integrated Security=True";
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
BindContrydropdown();
}
}
protected void BindContrydropdown()
{
SqlConnection con = new SqlConnection(strConnection);
con.Open();
SqlCommand cmd = new SqlCommand("select * from CountryTable", con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
con.Close();
ddlCountry.DataSource = ds;
ddlCountry.DataTextField = "CountryName";
ddlCountry.DataValueField = "CountryID";
ddlCountry.DataBind();
ddlCountry.Items.Insert(0, new ListItem("--Select--", "0"));
ddlState.Items.Insert(0, new ListItem("--Select--", "0"));
ddlRegion.Items.Insert(0, new ListItem("--Select--", "0"));
}
protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e)
{
int CountryID = Convert.ToInt32(ddlCountry.SelectedValue);
SqlConnection con = new SqlConnection(strConnection);
con.Open();
SqlCommand cmd = new SqlCommand("select * from StateTable where CountryID="+CountryID, con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
con.Close();
ddlState.DataSource = ds;
ddlState.DataTextField = "StateName";
ddlState.DataValueField = "StateID";
ddlState.DataBind();
ddlState.Items.Insert(0, new ListItem("--Select--", "0"));
if(ddlState.SelectedValue=="0")
{
ddlRegion.Items.Clear();
ddlRegion.Items.Insert(0, new ListItem("--Select--", "0"));
}
}
protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
int StateID = Convert.ToInt32(ddlState.SelectedValue);
SqlConnection con = new SqlConnection(strConnection);
con.Open();
SqlCommand cmd = new SqlCommand("select * from CityTable where StateID=" + StateID, con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
con.Close();
ddlRegion.DataSource = ds;
ddlRegion.DataTextField = "CityName";
ddlRegion.DataValueField = "CityID";
ddlRegion.DataBind();
ddlRegion.Items.Insert(0, new ListItem("--Select--", "0"));
}
}
