初步观察
原始查询可以重新格式化，以便于阅读，如下所示：
SELECT listings.end_date,
listings.user_id,
listings.title,
listings.auc_fp,
listings.id,
listings.auc_image1
FROM listings
JOIN (SELECT listing_id,
user_id,
bid maxBid
FROM bids
WHERE bid NOT IN (SELECT MAX(bid) FROM bids)
GROUP BY listing_id, user_id
) AS bids
ON listings.id = bids.listing_id
WHERE bids.user_id = 1
AND listings.end_date > NOW()
ORDER BY listings.list_ts DESC
我注意到别名为maxBid 的列不一定是任何列表的最高出价。此查询也仅适用于仍处于打开状态的列表。我不相信它会产生预期的答案。唯一排除的出价是包含任何列表的总体最高出价的出价。
TDQD — 测试驱动的查询设计
真正的问题是：
查找 $userid (= 1) 出价且是最高出价者的所有当前打开的列表。
是时候做 TDQD 了——测试驱动的查询设计；我的大脑工作速度不够快，无法一次完成所有操作。
每个列表的最高出价
SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
查找出价最高的用户是用户 1 的商家信息的出价
SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1
查找出价最高的用户是用户 1 的列表
SELECT l.*
FROM listings AS l
JOIN (SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1
) AS u
ON l.id = u.listing_id
限制查询打开列表
SELECT l.*
FROM listings AS l
JOIN (SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1
) AS u
ON l.id = u.listing_id
WHERE l.end_date > NOW()
您可以并且应该将* 替换为您感兴趣的确切列。如果您需要出价详细信息，也可以获取这些信息。
针对 Informix 进行测试
需要进行细微的语法更改——NOW() 被 CURRENT YEAR TO SECOND 替换——但这只会影响最后一个查询。在 DDL 上需要做更多的工作才能将语法转换为更接近 DBMS 中立的格式。 MySQL 有一些奇怪的约定。
未来读者请注意：将NOW() 或CURRENT YEAR TO SECOND 替换为2012-12-29 12:37:43 等值以获得相同的结果。数据中的列表从 `2013-01-10 00:00:001 开始过期。
查询 1：
SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id;
输出 1：
listing_id maxbid
34 95.37
40 103.00
38 507.00
41 94.00
48 76.00
6469 22.00
6472 5.00
37 511.00
31 100.00
查询 2：
SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1;
输出 2：
listing_id
34
37
48
6469
6472
查询 3：
SELECT l.end_date, l.user_id, l.title, l.id
FROM listings AS l
JOIN (SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1
) AS u
ON l.id = u.listing_id;
输出 3：
end_date user_id 标题 ID
2013-01-09 08:11:16 1 圣诞树 6469
2013-01-11 09:17:31 3 另一个测试项目6472
查询 4
SELECT l.end_date, l.user_id, l.title, l.id
FROM listings AS l
JOIN (SELECT b.listing_id
FROM bids AS b
JOIN (SELECT listing_id, MAX(bid) AS maxBid
FROM bids
GROUP BY listing_id
) AS m
ON m.listing_id = b.listing_id AND m.maxBid = b.bid
WHERE b.user_id = 1
) AS u
ON l.id = u.listing_id
WHERE l.end_date > CURRENT YEAR TO SECOND;
输出 4：
end_date user_id title id
2013-01-09 08:11:16 1 Christmas Tree 6469
2013-01-11 09:17:31 3 Another test item 6472