Create a from in Visual Studio Default.aspx :-
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!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>Fetch items from database in DropDownList</title>
<style type="text/css">
.style1
{
width: 93px;
}
.style2
{
width: 93px;
height: 26px;
}
.style3
{
height: 26px;
width: 96px;
}
.style4
{
width: 96px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<table style="width:22%;" align="center">
<tr>
<td class="style2">
Country :</td>
<td class="style3">
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"
onselectedindexchanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>
</td>
</tr>
<tr>
<td class="style1">
State :</td>
<td class="style4">
<asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True">
</asp:DropDownList>
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
Create Two Table in DataBase as follows :-
1) Country :-
2) State :-
Add details in the table whatever you want to add.
Now add two class :-
1) DataLayer.cs :-
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;
/// <summary>
/// Summary description for DataLayer
/// </summary>
public class DataLayer
{
SqlConnection cn;
SqlCommand cmd;
SqlDataAdapter da;
public DataLayer()
{
cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\C#\WebSites\DropDownList DataBase 1\App_Data\Database.mdf;Integrated Security=True;User Instance=True");
}
public DataSet get_country()
{
da = new SqlDataAdapter("Select* from Country", cn);
DataSet ds = new DataSet();
da.Fill(ds);
return ds;
}
public DataSet get_state(LogicLayer li)
{
da = new SqlDataAdapter("Select* from State where c_id=@id", cn);
da.SelectCommand.Parameters.AddWithValue("@id", li.country_id);
DataSet ds = new DataSet();
da.Fill(ds);
return ds;
}
}
2) LogicLayer.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
/// <summary>
/// Summary description for LogicLayer
/// </summary>
public class LogicLayer
{
public string country_id { get; set; }
public LogicLayer()
{
//
// TODO: Add constructor logic here
//
}
}
Now add following code in the Default.aspx.cs :-
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
LogicLayer li = new LogicLayer();
DataLayer dl = new DataLayer();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DropDownList1.DataSource = dl.get_country();
DropDownList1.DataTextField = "c_name";
DropDownList1.DataValueField = "c_id";
DropDownList1.DataBind();
DropDownList1.Items.Insert(0, "---Select---");
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
li.country_id = DropDownList1.SelectedValue;
DropDownList2.DataSource = dl.get_state(li);
DropDownList2.DataTextField = "s_name";
DropDownList2.DataValueField = "s_id";
DropDownList2.DataBind();
}
}
Output :-
1)
2)
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