Php单选按钮选择

Question

I am having trouble with getting the radio buttons to work with my select statement the issue lies somewhere in the buttons i think but i am unsure of this any and all help is appreciated

here is the code that i have currently. what i need to happen is for the page to refresh and sort the table to what has been selected by the button

    <?php require_once('dbadmin.php');?>
    <?php 
      session_start();
      $user = $_SESSION['user']; 
      if(!isset($user)){
        header("Location:admin_login.php");
      }
    ?>

    <h1>Reports</h1>
    <table border="1" style="width:100%">
  <tr>
    <th>First Name</th>
    <th>Last Name</th>
    <th>Email</th>
    <th>Distance</th>
  </tr>
   <?php
    include('dbadmin.php');
    $select = "SELECT `fname`, `lname`, `email`, `distance` FROM runner ORDER BY `lname`";
    $result = mysql_query($select) or die ('Oops! '.mysql_error($connect));

    if(isset($_POST['submit_sort'])){
        $radio = $_POST['radiosort']; 
        if($radio =='fname'){
          $select = "SELECT `fname`, `lname`, `email`, `distance` FROM runner ORDER BY `fname`";}
        else if($radio =='lname'){
        $select = "SELECT `fname`, `lname`, `email`, `distance` FROM runner ORDER BY `lname`";}
        else if($radio =='distance'){
          $select = "SELECT `fname`, `lname`, `email`, `distance` FROM runner ORDER BY `distance`";}
          $result = mysql_query($select) or die("Invalid query: ".mysql_error($connect));
        }
        if (mysql_num_rows($result) > 0) {  
        while($row = mysql_fetch_assoc($result)) {
        echo '<tr><td>'.$row['fname'].'</td>';
        echo '<td>'.$row['lname'].'</td>';
        echo '<td>'.$row['email'].'</td>';
        echo '<td>'.$row['distance'].'</td></tr>';
      }
      }
    ?>
    <form name="reports" id="reports" action="reports.php">
          <label for="submit_sort" style="font-weight:bold;">Sort By:</label><br>
          <input name="radiosort" type="radio" title="sort" id="lname" value="lname">
          <label for="lname">Last Name</label><br>
          <input name="radiosort" type="radio" title="sort" id="fname" value="fname">
          <label for="fname">First Name</label><br>
          <input name="radiosort" type="radio" title="sort" id="distance" value="distance">     
          <label for="distance">Distance</label><br><br>
          <input type="submit" name="submit_sort" title="submit_sort" id="submit" value="Submit">
      </form>
    </table>

Answer 1

$radio = $_POST['sort']; 

should be

$radio = $_POST['submit_sort'];