DEFINE $auction AS
<auction>
(
    FOR $u IN document("user.xml")//user_tuple
    RETURN
        <User>
            $u/userid,
            $u/name,
            $u/rating,
            (
                FOR $i IN document("items.xml")//item_tuple
                WHERE $i/offered_by = $u/userid
                RETURN
                    <Item>
                        $i/itemno,
                        $i/description,
                        $i/reserve_price,
                        (
                            FOR $b IN document("bids.xml")//bid_tuple
                            WHERE $b/itemno = $i/itemno
                            RETURN 
                                <Bid>
                                    $b/userid,
                                    $b/bid_amount,
                                    $b/bid_date,
                                </Bid> SORTBY(bid_date)
                         )
                     </Item>
            )
         </User>
)
</auction>