在dropbox on change事件时运行php函数，并从php函数返回一个表

我有下面的dropbox代码；

 <select name="Symptom" id="Symptomid" onchange="LSC()">

在dropbox中进行更改时，我想运行以下php代码；

<?php
$data = array();
{
  $symptoms_name = $_POST['Symptom'];
  $sql1 = mysql_query("SELECT name,description , comments
  FROM symptoms WHERE symptoms.name ='$symptoms_name'") or             
    die(mysql_error());     
    while($row1 = mysql_fetch_assoc($sql1)){
        $data[] = $row1;
    }
}
?>
<?php
if($data){
?>
<table border="1">
    <tr>
        <td>name</td>
        <td>description</td>
        <td>comments</td>
    </tr>
<?php
    if($data){
        foreach($data as $sy){
?>
    <tr>
        <td><?php echo $sy['name']; ?> </td>
        <td><?php echo $sy['description']; ?> </td>
        <td><?php echo $sy['comments']; ?> </td>
    </tr>
<?php
    }
}
?>
<?php
}
?>

</table>
}
and display this table under the dropbox on the original html .

我认为我们必须运行一个java脚本，该脚本将调用php函数并将表返回到原始html。

Kindly assist, I know we have to use ajax.
Regards
Azhar