How to Bind State Wise Citylist in DropDownList in ASP.NET

Here I am going to explain how to show state wise city list in DropDownList in Asp.net like below Image.

I have two tables in database like :

Now write the below code On the Page_Load in Asp.net

protected void Page_Load(object sender, EventArgs e)

{
SqlConnection cn = new SqlConnection("Data Source=BCILGGN13\\SQLEXPRESS;Initial catalog=Test; Uid=sa; Pwd=bcil;");
DataTable dt;
DataTable dt1;
SqlDataAdapter adap;
if (!IsPostBack)
{
ddlCity.AppendDataBoundItems = true;
ddlCity.Items.Insert(0, "-select-");
adap = new SqlDataAdapter("select * from State_List", cn);
dt = new DataTable();
adap.Fill(dt);
int j = 0;
if (dt.Rows.Count > 0)
{
j = 1;
for (int i = 0; i < dt.Rows.Count; i++)
{
ddlCity.Items.Add(dt.Rows[i]["State"].ToString());
ddlCity.Items[j].Attributes.Add("style", "color:red");
adap = new SqlDataAdapter("select City from city_list where state= '" + dt.Rows[i]["State"] + "'", cn);
dt1 = new DataTable();
adap.Fill(dt1);
for (int k = 0; k < dt1.Rows.Count; k++)
{
ddlCity.Items.Add(dt1.Rows[k]["City"].ToString());
}
j = dt1.Rows.Count +j+1;
}
}
}
}