Alright log on to PhpMyAdmin and make a new database called "users". We are going to insert 3 fields into a new table called useronline called timestamp, ip, and file. Lets dump the following code into the Users database using the form on the PhpMyAdmin page:
CREATE TABLE useronline (
timestamp int(15) DEFAULT '0' NOT NULL,
ip varchar(40) NOT NULL,
file varchar(100) NOT NULL,
PRIMARY KEY (timestamp),
KEY ip (ip),
KEY file (file)
);
Alright Now lets create the PHP script. Its rather large and lets hope you can follow along. Here is what we'll do in English:
Give the server info.
Get the time.
Insert the values of the person thats online into the mySQL, then create the Failed response if it failed.
Do the same thing but delete the user from the database when he leaves
Grab the results.
Output the results.
Finally, here is the PHP Code:
<?php
//fill in some basic info
$server = "localhost";
$db_user = "username"; s
$db_pass = "password";
$database = "users";
$timeoutseconds = 300;

//get the time
$timestamp = time();
$timeout = $timestamp-$timeoutseconds;

//connect to database
mysql_connect($server, $db_user, $db_pass);

//insert the values
$insert = mysql_db_query($database, "INSERT INTO useronline VALUES
('$timestamp','$REMOTE_ADDR','$PHP_SELF')");
if(!($insert)) {
print "Useronline Insert Failed > ";
}

//delete values when they leave
$delete = mysql_db_query($database, "DELETE FROM useronline WHERE timestamp<$timeout");
if(!($delete)) {
print "Useronline Delete Failed > ";
}

//grab the results
$result = mysql_db_query($database, "SELECT DISTINCT ip FROM useronline WHERE file='$PHP_SELF'");
if(!($result)) {
print "Useronline Select Error > ";
}

//number of rows = the number of people online
$user = mysql_num_rows($result);

//spit out the results
mysql_close();
if($user == 1) {
print("$user user online\n");
} else {
print("$user users online\n");
}
?>