Mine

$query = "SELECT p.pi_id, p.po_id, p.qty_ord, p.qty_rcv, p.complete, p.upc_id     FROM {$tblname['po_items']} AS p, {$tblname['upc']} AS u     WHERE p.po_id='$poID' 
    AND p.upc_id=u.upc_id";