Also do we need an action on the form? It is obligatory in XTHML 1.1 so sites in this doctype are not validates successfully.

<?

include 'db.php';

// Define post fields into simple variables
$first_name = $_POST['first_name'];
$last_name = $_POST['last_name'];
$email_address = $_POST['email_address'];
$username = $_POST['username'];
$info = $_POST['info'];

/* Let's strip some slashes in case the user entered
any escaped characters. */

$first_name = stripslashes($first_name);
$last_name = stripslashes($last_name);
$email_address = stripslashes($email_address);
$username = stripslashes($username);
$info = stripslashes($info);

/* Do some error checking on the form posted fields */

if((!$first_name) || (!$last_name) || (!$email_address) || (!$username)){
echo 'You did not submit the following required information! ‘;
if(!$first_name){
echo “First Name is a required field. Please enter it below.”;
}
if(!$last_name){
echo “Last Name is a required field. Please enter it below.”;
}
if(!$email_address){
echo “Email Address is a required field. Please enter it below.”;
}
if(!$username){
echo “Desired Username is a required field. Please enter it below.”;
}
include ‘join_form.html’; // Show the form again!
/* End the error checking and if everything is ok, we’ll move on to
creating the user account */
exit(); // if the error checking has failed, we’ll exit the script!
}

/* Let’s do some checking and ensure that the user’s email address or username
does not exist in the database */

$sql_email_check = mysql_query(“SELECT email_address FROM users WHERE email_address=’$email_address’”);
$sql_username_check = mysql_query(“SELECT username FROM users WHERE username=’$username’”);

$email_check = mysql_num_rows($sql_email_check);
$username_check = mysql_num_rows($sql_username_check);

if(($email_check > 0) || ($username_check > 0)){
echo “Please fix the following errors: “;
if($email_check > 0){
echo “Your email address has already been used by another member in our database. Please submit a different Email address!”;
unset($email_address);
}
if($username_check > 0){
echo “The username you have selected has already been used by another member in our database. Please choose a different Username!”;
unset($username);
}
include ‘join_form.html’; // Show the form again!
exit(); // exit the script so that we do not create this account!
}

?>