如何查看使用纪元时间有多少用户在线？

Question

i am having problem of see who's online and don't have any idea how to see who's online.what i am doing is updating mysql database using time(); whenever user log in or refreshes the page.

Then, lastactivity gets filled with epochtime for eg : 1387806657 or 1287373415. After that i select the lastactivity from database and use this condition but nothing happens.

<?
$result = mysql_query("SELECT lastactivity FROM users WHERE lastactivity!=0");            
while($rahul = mysql_fetch_assoc($result)){
$last = $rahul['lastactivity'];
echo $last;
}
?>
</br>
<?
if ($result < time()-3600) 
{
$hello = mysql_num_rows($result);
echo $hello;
}
else
{
echo "ERROR!";
}
?>

Answer 1

You could decide that any acticity in a 30 second interval from now means "online"

$early = time()-30;
$res = mysql_query("SELECT username,lastactivity FROM users WHERE lastactivity > $early") or die( mysql_error() );
while( $row = mysql_fetch_array($res) )
{
  echo $row['username'].' is online.<br>';
}

Answer 2

转到源并解析或查看Apache日志以查看正在加载哪些页面，该如何做？