ASP.NET webform基于Jquery,AJAX的三级联动

<select id="province">
<option value="0">--请选择省份--</option>
</select>
<select id="city">
<option value="0">--请选择城市--</option>
</select>
<select id="area">
<option value="0">--请选择地区--</option>
</select>

<script type="text/javascript">
$(document).ready(function () {
$.post("lianxi.aspx", { file2: 1 }, function (result) {
var province = result.split('|');
var newoption;
for (var i in province) {
new option = new Option(province[i], province[i]);
$("#province")[0].options.add(newoption);
}
})
$("#province").change(function () {
$("#city")[0].options.length = 1;
if ($("#province").val() == "0") {
return;
}
$.post("lianxi.aspx", { province: $("#province").val() }, function (result) {
var city = result.split('|'); var newoption;
for (var i in city) {
new option = new Option(city[i], city[i]);
$("#city")[0].options.add(newoption);
}
})
})
$("#city").change(function () {
$("#area")[0].options.length = 1;
if ($("#city").val() == "0") {
return;
}
$.post("lianxi.aspx", { city: $("#city").val() }, function (result) {
var area = result.split('|'); var newoption;
for (var i in area) {
new option = new Option(area[i], area[i]);
$("#area")[0].options.add(newoption);
}
})
})
})
</script>

protected void Page_Load(object sender, EventArgs e)
{
if (Request.Form["file2"] != null)
{
string sql = string.Format("select distinct province from proci");
DataTable dt = sqlhelper.helper.ExecuteQuery(sql);
string province = "";
for (int i = 0; i < dt.Rows.Count; i++)
{
province += "|" + dt.Rows[i][0].ToString();
}
Response.Write(province.Substring(1));
Response.End();
}
if (Request.Form["province"] != null)
{
string province = Request.Form["province"].ToString();
string sql2 = string.Format("select city from proci where province='{0}'", province);
DataTable dt2 = sqlhelper.helper.ExecuteQuery(sql2);
string city = "";
for (int j = 0; j < dt2.Rows.Count; j++)
{
city += "|" + dt2.Rows[j][0].ToString();
}
Response.Write(city.Substring(1));
Response.End();
}
if (Request.Form["city"] != null)
{
string city = Request.Form["city"].ToString();
string sql2 = string.Format("select dis from abcd where city='{0}'", city);
DataTable dt2 = sqlhelper.helper.ExecuteQuery(sql2);
string area = "";
for (int j = 0; j < dt2.Rows.Count; j++)
{
area += "|" + dt2.Rows[j][0].ToString();
}
Response.Write(area.Substring(1));
Response.End();
}
}