我有四张表1) Users 2) Products 3) Auctions 4) biddetails。用户和产品是主表和拍卖表中的产品ID就在那里。而biddetail表所有关键都有productid，userid和auctionid。
问题：我希望看到独特竞标者的每一件产品。
我的查询如下：
SELECT `p`.*, `a`.`id` as Auctionid, `a`.`enddate` as Enddate, `a`.`startdate` as Startdate, `a`.`bidprice` as Bidprice, `a`.`bidtype` as Bidtype, `a`.`starttime` as Starttime, `a`.`endtime` as Endtime, (SELECT username
FROM (select bid_price,u.username from biddetail as b join users as u on b.userid=u.id where b.auctionid=Auctionid group by b.bid_price,b.auctionid having count(b.bid_price)=1 order by b.bid_price asc Limit 0,1) t1 ) as Username FROM (`products` p) JOIN `auctions` a ON `a`.`productid`=`p`.`id` LEFT OUTER JOIN `biddetail` b ON `b`.`auctionid`=`a`.`id`
WHERE `a`.`status` = '0' AND `a`.`enddate`> '".$date."' AND `a`.`bidtype` = '1' GROUP BY `a`.`id` ORDER BY `a`.`id` desc