php post the drop down list value on the same page

I have a problem with the post, I can not post the value on the same page.

$result = mysqli_query($con, "SELECT * FROM bgu_characters") or die(mysqli_error($con));

$ID=$_POST['charactets'];
$result2 = mysqli_query($con, "SELECT * FROM bgu_characters where cid='$ID' ") or die(mysqli_error($con));

 while($row = mysqli_fetch_array($result2))
 {
?>
<form id= name="myform" method="post" action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>">
        
class="form-group">
            <label for="firstname">FirstName:</label>
            <input type="text" name="firstname" class="form-control" value="<?php echo $row['bgu_fname']; ?>">
        </div>

        <div class="form-group">
            <label for="lastname">LastName:</label>
            <input type="text" name="lastname" class="form-control" value="<?php echo $row['bgu_lname']; ?>">
        </div>
        <div class="form-group">
            <label for="beta">Description:</label>
            <textarea name="beta" class="form-control"> <?php if($row['bgu_description']){echo $row['bgu_description'];} ?></textarea>
        
<?php

}
?>

        <select name= method=post action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>"> 
         <?php
         
      while($row = mysqli_fetch_array($result))
      {
          $id =$row ['cid'];
          $FNames = $row ['bgu_fname'];
          $LNames = $row ['bgu_lname'];
          echo "$id'>$FNames $LNames $id";
      }
        ?>
        </select>

what I want to do is using a drop-down list to display all the data from MYSQL, once it selects the characters it should display all the information on the form, but somehow the drop-down list does not pass the id that is selected. I try the SQL using where cid = '2' and it works