Collect my Online users?

[Gayner]

How the hell do i go about doing this? lol my users table,

 

like on some sites like this 1 at bottom u can see everyone that is online,

 

i want to only show people that last clicked in 3minutes or less or don't show them online?

But all i got is  my user's table and no brain i even searched googled and tried to find a script to fetch online users but am lost,.. thx?

[Gayner]

$result = mysql_query("SELECT * FROM uonline WHERE session='$ses'");
$num = mysql_num_rows($result); 

if($num == "0"){
$result1 = mysql_query("INSERT INTO uonline (session, time)VALUES('$ses', '$time')");
}else{
$result2 = mysql_query("UPDATE uonline SET time='$time' WHERE session = '$ses'");
} 

$result3 = mysql_query("SELECT * FROM uonline"); 

$usersonline = mysql_num_rows($result3);
echo "There are: <b>".$usersonline."</b> users online";  

mysql_query("DELETE FROM uonline WHERE time<$timech");
?>

 

I got this but.... why does it use DELETE FROM ?

 

EDIT: Now i got this it works but how do i  still don't know why it uses DELETE FROM UAONLINE EACH REFRESH??

 

$ses = session_id();
$time = time();
$timech=$time-5;
$result = mysql_query("SELECT * FROM uonline WHERE session='$ses'");
$num = mysql_num_rows($result); 

if($num == "0"){
$result1 = mysql_query("INSERT INTO uonline (session, time)VALUES('$ses', '$time')");
}else{
$result2 = mysql_query("UPDATE uonline SET time='$time' WHERE session = '$ses'");
} 

$result3 = mysql_query("SELECT * FROM uonline"); 

$usersonline = mysql_num_rows($result3);
echo "There are: <b>".$usersonline."</b> users online";  

mysql_query("DELETE FROM uonline WHERE time<$timech");

 

this works but why does it use DELETE query at the end?

 

EDIT:::

 

OK so that query deletes all the sessions after 5seconds..

 

but that is dumb runnning a query every refresh is there anyway i can make it so it only runs after 20seconds? or 10seconds?