update panel for dropdownlist

Question

helo sir i m using category and subcategory using dropdown lists soi have connected it with databaseit works fine but i have to select category in dropdown list then automatically subcategry get reflected in second dropdown list without page refreshing . so pls help me i m stucked here....

Satyapriya Nayak · Answer

Untitled Page ForeColor=Red Width=100px> AppendDataBoundItems=true runat=server Height=20px Width=156px onselectedindexchanged=DropDownList1_SelectedIndexChanged Font-Bold=True ForeColor=#FF9900> using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Data.SqlClient; namespace Ajax_dropdown { public partial class _Default : System.Web.UI.Page { string strConnString = ConfigurationManager.ConnectionStrings[ConnectionString].ConnectionString; string str; SqlCommand com; protected void Page_Load(object sender EventArgs e) { //SqlConnection con = new SqlConnection(strConnString); DropDownList1.AutoPostBack = true; SqlConnection con = new SqlConnection(strConnString); if (!IsPostBack) { DropDownList1.Items.Add(Choose City); con.Open(); str = select * from area ; com = new SqlCommand(str con); SqlDataReader reader = com.ExecuteReader(); while (reader.Read()) { DropDownList1.Items.Add(reader[city].ToString()); } reader.Close(); con.Close(); } DropDownList2.Items.Clear(); } protected void DropDownList1_SelectedIndexChanged(object sender EventArgs e) { DropDownList1.AutoPostBack = true; SqlConnection con = new SqlConnection(strConnString); con.Open(); str = select * from area where city=' + DropDownList1.SelectedValue + '; com = new SqlCommand(str con); SqlDataReader reader = com.ExecuteReader(); while (reader.Read()) { DropDownList2.Items.Add(reader[stdcode].ToString()); } reader.Close(); con.Close(); } } }