Example code:
global $smcFunc;
$dbresult = $smcFunc['db_query']('', "
SELECT
c.ID_COMMENT, c.ID_LISTING, c.comment, c.date, c.ID_MEMBER, m.member_name,
m.real_name FROM {db_prefix}class_comment as c
LEFT JOIN {db_prefix}members AS m ON (c.ID_MEMBER = m.ID_MEMBER)
WHERE c.approved = 1 ORDER BY c.ID_COMMENT DESC LIMIT 10");
while($row = $smcFunc['db_fetch_assoc']($dbresult))
{
echo '<a href="' . $scripturl . '?action=classifieds;sa=view;id=' . $row['ID_LISTING'] . '">' . substr($row['comment'], 0, 100) .'</a><br />
by ';
if($row['real_name'] != '')
echo '<a href="' . $scripturl . '?action=profile;u=' . $row['ID_MEMBER'] . '">' . $row['real_name'] . '</a>';
else
echo '' . $txt['class_guest']. '';
echo '<br />
', timeformat($row['date']), '
<hr /><br />';
}