$sql = "UPDATE user
            SET username = '".mysql_real_escape_string($_POST[nusername])."'
            SET password = '".mysql_real_escape_string($_POST[npassword])."'
            SET name = '".mysql_real_escape_string($_POST[nname])."'
            SET surname = '".mysql_real_escape_string($_POST[nsurname])."'
            SET role = '".mysql_real_escape_string($_POST[nrole])."'
            WHERE username='".mysql_real_escape_string($_POST[us])."'";

// test
echo $sql;

mysql_query($sql);