Bindonedropdowntoanotherdropdown.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Bindonedropdowntoanotherdropdown.aspx.cs" Inherits="Bindonedropdowntoanotherdropdown" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
.auto-style1 {
width: 100%;
}
.auto-style2 {
width: 167px;
}
.auto-style3 {
width: 167px;
height: 62px;
}
.auto-style4 {
height: 62px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<table class="auto-style1">
<tr>
<td class="auto-style3">Country</td>
<td class="auto-style4">
<asp:DropDownList ID="CountryDropDownList" runat="server" AutoPostBack="True" Height="16px" OnSelectedIndexChanged="CountryDropDownList_SelectedIndexChanged" Width="253px">
</asp:DropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="CountryDropDownList" Display="Dynamic" ErrorMessage="Country is Required" ForeColor="Red" InitialValue="Select Country" SetFocusOnError="True"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="auto-style2">City</td>
<td>
<asp:DropDownList ID="CityDropDownList" runat="server" Height="16px" Width="253px">
</asp:DropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="CityDropDownList" Display="Dynamic" ErrorMessage="City is Required" ForeColor="Red" InitialValue="Select City" SetFocusOnError="True"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="auto-style2"> </td>
<td>
<asp:Button ID="SubmitButton" runat="server" OnClick="SubmitButton_Click" Text="SUBMIT" />
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
Bindonedropdowntoanotherdropdown.aspx.cs
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;
using System.Configuration;
public partial class Bindonedropdowntoanotherdropdown : System.Web.UI.Page
{
string cs = ConfigurationManager.ConnectionStrings["dbcs"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
BindCountryDDL();
}
}
void BindCountryDDL()
{
SqlConnection con = new SqlConnection(cs);
string query = "select * from country";
SqlDataAdapter sda = new SqlDataAdapter(query, con);//It is use to Execute query
//Datable me value aayage SqlDataAdapter se
DataTable data = new DataTable();
sda.Fill(data);
CountryDropDownList.DataSource = data;
CountryDropDownList.DataTextField = "country_name";
CountryDropDownList.DataValueField = "country_id";
CountryDropDownList.DataBind();
//Select item show hoga dropdown list me
ListItem selectItem = new ListItem("Select Country","Select Country");
selectItem.Selected = true;
//Phala option me select country show hoga[It can show in 0 index]
CountryDropDownList.Items.Insert(0,selectItem);
}
void BindCityDDL(int country_id)//int is datatype and country_id is parameter[Parameter pass ho raha ha]
{
SqlConnection con = new SqlConnection(cs);
string query = "select * from city where c_id = @country_id";
SqlDataAdapter sda = new SqlDataAdapter(query, con);//It is use to Execute query
//sda se command select kar raha ha
sda.SelectCommand.Parameters.AddWithValue("@country_id", country_id);
//Datatable me value aayage SqlDataAdapter se
DataTable data = new DataTable();
sda.Fill(data);
CityDropDownList.DataSource = data;
CityDropDownList.DataTextField = "city_name";
CityDropDownList.DataValueField = "city_id";
CityDropDownList.DataBind();
//Select item show hoga dropdown list me
ListItem selectItem = new ListItem("Select City", "Select City");
selectItem.Selected = true;
//Phala option me select city show hoga[It can show in 0 index]
CityDropDownList.Items.Insert(0, selectItem);
}
protected void CountryDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
//Upper me country id int diya gaya ha usili liya Integer me convert karna ha
int country_id = Convert.ToInt32(CountryDropDownList.SelectedValue);
BindCityDDL(country_id);
}
catch(Exception ex)
{
Response.Write("<script>alert('Country is Required')</script>");
}
}
protected void SubmitButton_Click(object sender, EventArgs e)
{
Response.Write("Selected Country is:"+CountryDropDownList.SelectedItem.ToString()+"<br>");
Response.Write("Selected Country Id is:" + CountryDropDownList.SelectedValue.ToString()+"<br>");
Response.Write("Selected City is:" + CityDropDownList.SelectedItem.ToString()+"<br>");
Response.Write("Selected Country Id is:" + CityDropDownList.SelectedValue.ToString()+"<br>");
}
}//Auto Postback True karna pa selected index change ka event fire hoga
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