我已经扩展来加载我的下拉列表从db，我只需要一种方法来连接onchange方法在我的第一个下拉列表，其次，请看代码。感谢任何帮助。

追加最新的代码：

<select id="country"  onchange="getStateByCountryId()"></select> <br />
<select id="state"></select>  <br />


$(document).ready(function() { 
     var options = {
         type: "POST",url: "SearchPage.aspx/LoadCountry",data: "{}",contentType: "application/json; charset=utf-8",dataType: "json",success: function(msg) {

             var returnedArray = msg.d;
             country = $("#country"); 
              country.append('<option>Select a Country</option>'); 

             for (i = 0; i < returnedArray.length; i++) {
                  country.append("<option value='" + returnedArray[i].Id + "'>" + returnedArray[i].Name + "</option>");
             }


         }
     };
     $.ajax(options);
 });


function getStateByCountryId() {

     $("#country").change(function() 
     { 
         var _selected = $("#country").val();
         var options = 
         {
             type: "POST",url: "SearchPage.aspx/StateBy",data: "{'countryId':'" + _selected + "'}",success: function(msg) {
                $('#state').empty(); 
                 var returnedArray = msg.d;


                 state = $("#state");
                 for (var i = 0; i < returnedArray.length; ++i) {
                     state.append("<option value='" + returnedArray[i].Id + "'>" + returnedArray[i].Name + "</option>");
                 }
             }
         };
         $.ajax(options);
     });
 }

但不填充？我在做什么是你怎么想的？

谢谢。