<?php
    $con = mysql_connect("localhost", "root", "H@lp2012") or die(mysql_error());
    $db = mysql_select_db("registerdb", $con) or die(mysql_error());
    $query = mysql_query("SELECT * FROM `users`") or   die(mysql_error());
        $query2 = mysql_query("SELECT * FROM users WHERE username = ".$user_name);

        $user_name = $_POST['userName'];
    $user_fname = $_POST['userFName'];
    $user_email = $_POST['userEmail'];
    $user_pass = $_POST['userPassword'];

    if(!empty($user_name) && !empty($user_fname) && !empty($user_email) && !empty($user_pass) && mysql_num_rows($query2) == 0) {

        mysql_query("INSERT INTO `users` (`fullname`, `username`,`email` ,`password`)
        VALUES ('".$user_fname."', '".$user_name."','".$user_email."','".$user_pass."')") or die (mysql_error());
        echo "You have succefully registered now!";
    }
    else
    {
    echo "Please fill out all the fields!";
    }
?>