$sSQL .= ' FROM us_postcode WHERE postcode NOT IN';
$sSQL .= ' (SELECT postcode FROM location_postcode';
$sSQL .= " WHERE country_code = 'us')";
$sSQL .= ' FROM us_postcode WHERE postcode NOT IN';
$sSQL .= ' (SELECT postcode FROM location_postcode';
$sSQL .= " WHERE country_code = 'us')";