How to do multiple dropdown list??

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Configuration;

using MySql.Data.MySqlClient;

using System.Data;

namespace entry

{

public partial class def2 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

populatedept();

}

}

public void populatedept()

{

MySqlConnection con = new MySqlConnection(ConfigurationManager.ConnectionStrings["MySqlConnectionString"].ConnectionString);

con.Open();

MySqlCommand cmd = new MySqlCommand("select id,department from department_names", con);

MySqlDataAdapter adpt = new MySqlDataAdapter(cmd);

DataTable dt = new DataTable();

adpt.Fill(dt);

DropDownList1.DataSource = dt;

DropDownList1.DataBind();

DropDownList1.DataTextField = "department";

DropDownList1.DataValueField = "id";

DropDownList1.DataBind();

}

protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)

{

if (!IsPostBack)

{

simpledept();

}

}

public void simpledept()

{

MySqlConnection con = new MySqlConnection(ConfigurationManager.ConnectionStrings["MySqlConnectionString"].ConnectionString);

con.Open();

MySqlCommand cmd = new MySqlCommand("select id,functions from function_list",con);

MySqlDataAdapter adpt = new MySqlDataAdapter(cmd);

DataTable dt = new DataTable();

adpt.Fill(dt);

DropDownList2.DataSource = dt;

DropDownList2.DataBind();

DropDownList2.DataTextField = "functions";

DropDownList2.DataValueField = "id";

DropDownList2.DataBind();

}

}

}