php - Get selected text from combox to a variable -

i want select school year combobox , use search classes letter year selected. need put selected text variable.

$yeardb = "select distinct `year` `class`";          $do_year = mysqli_query($connectdb, $yeardb);          $num_year = mysqli_num_rows($do_year);      year:     <form method="post" >    <select id="yearcb" name="year" onchange="document.getelementbyid('selected_text').value=this.options[this.selectedindex].text">             <?php                 ($i=0; $i<$num_year; $i++)                  {                     $yr = mysqli_fetch_array($do_year);                     echo'<option value="'.$i.'">'.$yr ['year'].'</option>';                 }             ?>         </select>         <input type="hidden" name="selected_text" id="selected_text" />         </form>          <?php          if(isset($_post['selected_text']))         {              $value = $_post['year'];              $make = mysql_real_escape_string($_post['selected_text']);         }          $classdb = "select `class` `classes` `year` =".$make;         $do_class = mysqli_query($connectdb, $classdb);          $num_class = mysqli_num_rows($do_class);         ?> 

in jquery

<select id="yearcb" name="year" onchange="funname(this.value)">     </select>     <input type="hidden" name="selected_text" id="selected_text" />      function funname(val)    `/*function set value*/` {     $("#selected_text").val(val); }