<?
header("Content-type: text/plain");

include('../tb/tb.inc.php');

$username = $_REQUEST['user'];
$password = $_REQUEST['pass'];
$ip = $_SERVER['REMOTE_ADDR'];

$id = intval($_REQUEST['id']);
$progid = intval($_REQUEST['progid']);
$text = $_REQUEST['text'];

if ($username)
  quicklogin($username, $password);

echo "user_id=$user_id\n";

if (!$id) die("Nothing to do.");
if (!$progid) die("Need prog ID.");

$where = "c_snippetid=$id and c_programid=$progid";
dbDo("start transaction");
$oldText = dbSingleValue("select c_text from tb_comment where $where");
if (!strcmp($oldText, $text)) die ("Text unchanged!");

# save old comment
dbUpdate("insert into tb_comment_old
  (c_snippetid, c_programid, c_author, c_modified, c_text)
  select c_snippetid, c_programid, c_author, c_modified, c_text
  from tb_comment where $where");

# delete
dbDo("delete from tb_comment where $where");

# update
$commentID = dbInsert("insert into tb_comment set
  c_snippetid=$id,
  c_programid=$progid,
  c_clientip=".dbQuote($clientIP).",
  c_created=now(),
  c_modified=now(),
  c_text=".dbQuote($text).",
  c_author=$user_id");

dbDo("commit");

echo "Done. Comment ID: $commentID";

?>

Actual PHP code from web site. (tb-int/...)