When I have two or more comments on a post, it show the post again and the next comment underneath it. How do I make it so it shows only the post once and the comments underneath it if there are multiple comments?

$sql_posts = mysql_query("SELECT * FROM posts ORDER BY post_date DESC ");

$postDisplayList = ""; 

while($row = mysql_fetch_array($sql_posts)){
$postid = $row["id"];
$uid = $row["user_id"];
$the_post = $row["post"];
$post_date = $row["post_date"];


$sql_mem_data = mysql_query("SELECT id, username, firstname, lastname FROM users WHERE id='$uid' LIMIT 1");
while($row = mysql_fetch_array($sql_mem_data)){
        $uid = $row["id"];
        $username = $row["username"];
        $firstname = $row["firstname"];
        $lastname = $row["lastname"];

}
$sql_com_data = mysql_query("SELECT * FROM comments WHERE post_id='$postid'  ");
while($row = mysql_fetch_assoc($sql_com_data)){
        $uid1 = $row["user_id"];
        $comment = $row["comment"];
        $whencomment = $row["comment_date"];

$sql_com_data_user = mysql_query("SELECT * FROM users WHERE id='$uid1' ");
while($row = mysql_fetch_array($sql_com_data_user)){
        $username1 = $row["username"];
        $firstname1 = $row["firstname"];
        $lastname1 = $row["lastname"];
}
        $postDisplayList .= '
            <table width="100%" align="center" cellpadding="6" style="background-color:#F2F2F2; ">
    <tr>
      <td width="93%" bgcolor="#F2F2F2" style="line-height:1.5em;" valign="top">
     <span class="liteGreyColor textsize9"> ' . $post_date . ' <a href="profile.php?id=' . $uid . '"><strong>' . $username . '</strong></a></span><br />
     <span class="textsize14"> ' . $the_post . '</span>
        </td>
    </tr>
     <tr>
      <td width="93%" bgcolor="#F2F2F2" style="line-height:1.5em;" valign="top">
     <span class="liteGreyColor textsize9"> ' . $whencomment . ' <a href="profile.php?id=' . $uid1 . '"><strong>' . $username1 . '</strong></a></span><br />
     <span class="textsize14"> ' . $comment . '</span>
        </td>
    </tr>
  </table>';