依赖下拉列表在php中工作，而在codeigniter中不工作

在下面的代码中，当我在php中工作时，当选择考试名称时，下拉列表工作良好，相应的课程代码来了，当我选择相应的科目代码来了。但现在我创建了控制器，并在codeigner中调用视图。当我选择exam_name时，它没有填充值，当我点击上传时，它显示课程代码值，没有填充subject_code，当我单击上传时，会填充subject-code。所以任何人都请帮我。

            Upload1_site (controller)
                   <?php
              class Upload1_site extends ci_controller
                 {
                  function index()
            {   
                $this->load->view('new_view');

            } 
           function upload()
            {   
                $this->load->view('new1_view');

            } 

             }//end of class         ?>


              new_view (View 1)
        <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
        <script type="text/javascript">
         $(document).ready(function(){
     $(".hai").change(function()
     {
     var id=$(this).val();
     // Please find the course_code, course_code was not found
      var dataString = 'course_code='+ id;
        $.ajax
        ({
            type: "POST",
            url: "upload1_site/upload",
            data: dataString,
            cache: false,
            success: function(html)
            {
                $(".hai2").html(html);
            } 
        });
    });
    $(".hai2").change(function()
    {
        var id2=$("#hai2").val();
        alert(id2);
        var dataString = 'subject_code='+ id2;
        $.ajax
        ({
            type: "POST",
            url: "upload1_site/upload",
            data: dataString,
            cache: false,
            success: function(html)
            {
                $(".hai3").html(html);
            }
        });
    });
           });
         </script>
         </head>

     <form enctype="multipart/form-data" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
         File to import: 
      <input size='30' type='file' name='filename'>
         <br>
      Select Exam name:
     <select name="hai" class="hai" id="hai">
          <?php
          mysql_connect("localhost", "root", "") or die("Error connecting to database: ".mysql_error());
            mysql_select_db("slseatapp") or die(mysql_error());
          $query="select  distinct exam_name from examcourse";
          $result = mysql_query($query);
           while($nt=mysql_fetch_array($result)) {
           echo "<option value='".$nt['exam_name']."'>".$nt['exam_name']."</option>";
            }
            ?>
           </select>
               <br> 
           <span class="hai2">
    Course code:
    <select name="hai2" id="hai2">
    <?php if($_REQUEST['hai']){?>
    <option>Select</option> 
     <?php
        $query="SELECT distinct course_code FROM examcourse where exam_name =  '".$_REQUEST['hai']."' ";
        $result = mysql_query($query);
        while($nt=mysql_fetch_array($result)) {
        echo "<option value='".$nt['course_code']."'>".$nt['course_code']."</option>";
        }
    ?>
     <?php }else{?>
    <option>Select</option>
     <?php }?>
       </select>
         </span>
         <br>
          <span class="hai3">
    Subject code:
    <select name="hai3" id="hai3">
    <?php if($_REQUEST['hai2']){?>
    <option>Select</option>
     <?php
        $query="SELECT distinct subject_code FROM coursesubject where course_code = '".$_REQUEST['hai2']."'";
        $result = mysql_query($query);
        while($nt=mysql_fetch_array($result)) {
        echo "<option value='".$nt['subject_code']."'>".$nt['subject_code']."</option>";
        }
    ?>
      <?php }else{?>
    <option>Select</option>
        <?php }?>
            </select>
           </span>
                <br>
          <input type="submit" name="submit" value="Upload"></form>

         <?php 
         mysql_connect("localhost", "root", "") or die("Error connecting to database: ".mysql_error());
           mysql_select_db("slseatapp") or die(mysql_error());
              //Upload File 
           if (isset($_POST['submit'])) { 
           if (is_uploaded_file($_FILES['filename']['tmp_name'])) { 
         //Import uploaded file to Database 
           $row = 1; 
            $handle = fopen($_FILES['filename']['tmp_name'], "r"); 
              $var = $_POST['hai'];
               $var2 = $_POST['hai2'];
              $var3 = $_POST['hai3'];
           //$res=mysql_fetch_array(mysql_query("SELECT subject_code FROM coursesubject where course_code = '".$var1."'"));
         while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) { 
             //Update Database Values 
            $import="insert into student_table (id,register_number,name,course_code,subject_code,exam_name) VALUES('".mysql_real_escape_string($data[0])."', '".mysql_real_escape_string($data[1])."','".mysql_real_escape_string($data[2])."','$var2','".$var3."','$var')"; 
          //$import="replace into  student_table (id,register_number,name,course_code,subject_code,exam_name) VALUES('".mysql_real_escape_string($data[0])."', '".mysql_real_escape_string($data[1])."','".mysql_real_escape_string($data[2])."','$var','$var1','$var2')";

               mysql_query($import) or die(mysql_error()); 
            }
       fclose($handle);
        echo"<script>alert('Uploaded Successfully');</script>";  
           }else{
      echo"<script>alert('Failed');</script>"; 
         }

        } 
        ?>

               new2_view (view 2)
          <script language="javascript">
            function changeSelection(value){
           var length = document.getElementById("hai3").options.length;
               if(value == 0){
            for(var i = 1;i<length;i++)
              document.getElementById("hai3").options[i].selected = "selected";
             document.getElementById("hai3").options[0].selected = "";
               }
                   }
                 </script>
               <?php
               mysql_connect("localhost", "root", "") or die("Error connecting to database: ".mysql_error());
               mysql_select_db("slseatapp") or die(mysql_error());
             if($_POST['course_code']){
                @$exam_name=$_POST['course_code'];
                ?>
                Course code: <select name="hai2" id="hai2">
                <option >Select</option>
                 <?php
                      $query="SELECT distinct course_code FROM examcourse where exam_name = '$exam_name' ";
                    $result = mysql_query($query);
                 while($nt=mysql_fetch_array($result)) {
            echo "<option value='".$nt['course_code']."'>".$nt['course_code']."</option>";
               }
                 ?>
              </select>
             <?php }
                if($_POST['subject_code']){
                 @$subject_code=$_POST['subject_code'];
                 ?>
                Subject code:
               <select name="hai3" multiple onChange="changeSelection(this.value)" id="hai3">
      <option value="0">Select</option>
     <?php
        $query="SELECT subject_code FROM coursesubject where course_code = '".$subject_code."'";
        $result = mysql_query($query);
        while($nt=mysql_fetch_array($result)) {
        echo "<option value='".$nt['subject_code']."'>".$nt['subject_code']."</option>";
        }
             ?>
                  </select>
                   <?php }?>