ajax例子

<form id="Form1" method="post" runat="server">
<asp:DropDownList id="goodsType" style="Z-INDEX: 101; LEFT: 216px; POSITION: absolute; TOP: 88px"
runat="server" Width="184px"></asp:DropDownList>
<asp:DropDownList id="pptype" style="Z-INDEX: 102; LEFT: 536px; POSITION: absolute; TOP: 96px" runat="server"
Width="152px"></asp:DropDownList></form>
<script language="javascript">
<!--
var pptypelist = document.getElementById("<%=pptype.ClientID%>");

function loadPP(goodsType)
{
var goodsID = document.getElementById("goodsType").value;//goodsType.options[goodsType.selectedIndex].value;
if(goodsID >0)
{
Demo.getPP(goodsID,loadPP_CallBack);
}
else
{
pptypelist.options.length = 0;
}
}
//callback we told Ajax.Net to pass the response tos
function loadPP_CallBack(response)
{
if(response.error != null)
{
alert(response.error); //we should probably do better than this
return;
}
var ds = response.value;
if(ds == null ||typeof(ds) !="object")
{
return;
}
pptypelist.options.length = 0;
for (var i = 0; i < ds.Tables[0].Rows.length; i++)
{
//pptypelist.options[pptypelist.options.length] = new Option(ds.Tables[0].Rows[i].PPName, ds.Rows[i].PPID);
var name = ds.Tables[0].Rows[i].ppName;
var ID = ds.Tables[0].Rows[i].PPID;
document.getElementById("pptype").options.add(new Option(name,ID));
}
}


//-->
</script>

public class Demo : Page
 {
  protected System.Web.UI.WebControls.DropDownList goodsType;
  protected System.Web.UI.WebControls.DropDownList pptype;
 
  private void Page_Load(object sender, System.EventArgs e)
  {
   Ajax.Utility.RegisterTypeForAjax(typeof(Demo));
   if(!this.IsPostBack)
   {
       goodsType.DataSource = bindData();
    goodsType.DataTextField = "GoodsTypeName";
    goodsType.DataValueField ="GoodsType_ID";
    goodsType.DataBind();

    goodsType.Items.Insert(0,new ListItem("--please select item --"));
    goodsType.Attributes.Add("onchange","loadPP(this);");
   }
  }
  public DataTable bindData()
  {
     SqlConnection conn = new SqlConnection("server=.;database=cvbbs; uid=sa;pwd=");
     conn.Open();
     SqlDataAdapter da = new SqlDataAdapter("select * from D_GoodsTypeInfo",conn);
     DataTable dt = new DataTable();
     da.Fill(dt);
     return dt;
  }
  [Ajax.AjaxMethod(Ajax.HttpSessionStateRequirement.Read)]
  public DataSet getPP(int goodsTypeID)
  {
   //string str ="select * from D_PP where GoodsType_ID = "+goodsTypeID;
   SqlConnection conn = new SqlConnection("server=.;database=cvbbs; uid=sa;pwd=");
   conn.Open();
   SqlCommand  cmd = new SqlCommand();
   cmd.Connection = conn;
   cmd.CommandText ="p_GoodsTypeGetPP";
   cmd.CommandType = CommandType.StoredProcedure;
   SqlDataAdapter da = new SqlDataAdapter(cmd);
   cmd.Parameters.Add("@GoodsID",goodsTypeID);
   DataSet ds = new DataSet();
   da.Fill(ds);
   if(ds!=null && ds.Tables[0].Rows.Count>0)
    return ds;
   else
    return null;
  }