i have difficulties with the sql part - php

Question

I posted a code below about my website. In this code i want to update rows in my database, if the user changed the name of the topic on the website's form. Everything is working except the sql part. I mean the part where:"LIMIT 1 OFFSET '$x'" this part of the sql code is not good for some reason, but i don't know why. I tested it in xampp phpmyadmin and it works but here something just wrong.
<?php
$sql = "SELECT topicname, username, created, COUNT(commentid)
FROM user, topic, comment
WHERE topic.topicid = comment.whichtopic
AND user.userid = topic.owner
AND user.username = '" . $_SESSION['user_name '] . "'
GROUP BY topicname ";
$lekerdezes = mysql_query($sql);
$num_rows = mysql_num_rows($lekerdezes); ?>
<?php
if (isset($_POST['delete']))
{
if (!empty($_POST['forumnev']))
{
for ($x = 0; $x < $num_rows; $x++)
{
foreach ($_POST['forumnev'] as $selected)
{
$seged = mysql_query("SELECT created FROM topic WHERE
created IN (SELECT created FROM user, topic, comment WHERE topic.topicid = comment.whichtopic
AND user.userid = topic.owner AND user.username = '" . $_SESSION['user_name '] . "'
GROUP BY topicname ORDER BY created)
LIMIT 1 OFFSET '$x'");
if (!$seged)
{
echo mysql_error();
}
$seged2 = mysql_fetch_array($seged);
$seged2 = $seged2[0];
if (!$seged2)
{
echo mysql_error();
}
$sql = mysql_query("UPDATE topic SET topicname = '$selected' WHERE created = '$seged2'");
}
}
header("Location: topicedit.php");
}
}
?>

Answer 1

Try updating as follows:(Hope your limit: 1 and offset: $x)
$seged = mysql_query("SELECT created FROM topic WHERE created IN (SELECT created
FROM user,topic,comment
WHERE topic.topicid = comment.whichtopic
AND user.userid = topic.owner
AND user.username = '". $_SESSION['user_name'] ."'
GROUP BY topicname
ORDER BY created)
LIMIT $x, 1");