การสร้าง PHP User online

1. สร้างฐานข้อมูล และสร้างตาราง user_online

CREATE TABLE `user_online` (
`session` char(100) NOT NULL default '',
`time` int(11) NOT NULL default '0'
) TYPE=MyISAM;

2. เขียนโค๊ด้านล่างแล้วลอง run

<?
session_start();
$session=session_id();
$time=time();
$time_check=$time-600; //SET TIME 10 Minute

$host="localhost"; // Host name
$username="UserName"; // Mysql username
$password="Password"; // Mysql password
$db_name="Database"; // Database name
$tbl_name10="user_online"; // Table name

// ติดต่อ databse
mysql_connect("$host", "$username", "$password")or die("cannot connect to server");
mysql_select_db("$db_name")or die("cannot select DB");

$sql="SELECT * FROM $tbl_name10 WHERE session='$session'";
$result=mysql_query($sql);

$count=mysql_num_rows($result);

if($count=="0"){
$sql1="INSERT INTO $tbl_name10(session, time)VALUES('$session', '$time')";
$result1=mysql_query($sql1);
}
else {
"$sql2=UPDATE $tbl_name10 SET time='$time' WHERE session = '$session'";
$result2=mysql_query($sql2);
}

$sql3="SELECT * FROM $tbl_name10";
$result3=mysql_query($sql3);

$count_user_online=mysql_num_rows($result3);

echo "User online : $count_user_online ";

// ถ้าครบ 10 นาที session
$sql4="DELETE FROM $tbl_name10 WHERE time<$time_check";
$result4=mysql_query($sql4);

mysql_close();


?>