Showing no. of users on your site using PHP/MySQL

How to show the no. of users online on your site using PHP & MySQL.

Step1: Creating the database
Create a new table called 'useronline', with 3 fields inside a table. The fields are timestamp, ip and file. Below is the SQL to create the table.

Code:

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)
 );

Step 2: The PHP Script

PHP:

<?php
 //Put your basic server info here
 $server = "localhost"; //normally localhost
 $db_user = "username"; //your MySQL database username
 $db_pass = "password"; //your MySQL database password
 $database = "users";
 $timeoutseconds = 300;
 
 //this is where PHP gets the time
 $timestamp = time();
 $timeout = $timestamp-$timeoutseconds;
 
 //connect to database
 //$server = localhost probably
 //$db_user = your MySQL database username
 //$db_pass = //your MySQL database password
 mysql_connect($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");
 }
 ?>
 

The script basically works like this. It receives server information and gets the time. In MySQL it fills in the values of the person online and puts up a message if it fails. After a timeout period MySQL deletes the user i.e. we assume that the user is not on our site anymore.