با سلام
<?php
$username=$_POST['username'];
$email=$_POST['email'];
$con=mysql_pconnect("localhost","root","");
if(!$con)
{die('could not connect');}
mysql_select_db("register",$con);
mysql_query("SET NAMES UTF8");
mysql_set_charset("utf8");
// check kardan username AND email
$sql="SELECT `id` FROM `users` WHERE `username`='$username' OR `email`='$email'";
$result = mysql_query($sql);
if(mysql_num_rows($result)>='1') {
echo "<script>alert('نام کاربری و یا آدرس ایمیل تکراری می باشد')</script>";
echo "<meta http-equiv='refresh' content='0; URL=newuser.php'>"; exit();
} else {
$sql="insert into users(username,email,password,repassword)
values('$_POST[username]','$_POST[email]','$_POST[password]','$_POST[repassword]')";
$result = mysql_query($sql);
if($result)
{
echo mysql_affected_rows().'<b> Information Save Success </b>';
} }
mysql_close($con);
?>