我正在编写一个 SQL 查询,它将返回某个用户失去的拍卖列表,例如在 eBay 上。
这是我的 table :
bid_id bid_belongs_to_auction bid_from_user bid_price
6 7 1 15.00
8 7 2 19.00
13 7 1 25.00
有问题的区域是这个(取 self 的完整查询,放在问题的末尾):
AND EXISTS (
SELECT 1
FROM bids x
WHERE x.bid_belongs_to_auction = bids.bid_belongs_to_auction
AND x.bid_price > bids.bid_price
AND x.bid_from_user <> bids.bid_from_user
)
问题是查询返回了所有出价更高的拍卖,但忽略了用户更高的出价。
所以,上面的查询有效的例子:
bid_id bid_belongs_to_auction bid_from_user bid_price
6 7 1 15.00
7 7 2 18.00
在这种情况下,用户 1 被退回为输掉了拍卖,因为有另一个出价高于该用户的出价。
但是,这里是查询不起作用的时候:
bid_id bid_belongs_to_auction bid_from_user bid_price
6 7 1 15.00
8 7 2 19.00
13 7 1 25.00
在这种情况下,用户 1 被错误地返回为输掉了拍卖,因为有另一个出价高于他之前的出价,但用户已经给出了更高的出价。
如果它很重要,这是我的完整查询,但我认为没有必要解决上述问题,但我还是将其发布在这里:
$query = "
SELECT
`bid_belongs_to_auction`,
`auction_unixtime_expiration`,
`auction_belongs_to_hotel`,
`auction_seo_title`,
`auction_title`,
`auction_description_1`
FROM (
SELECT
`bid_belongs_to_auction`,
`bid_from_user`,
MAX(`bid_price`) AS `bid_price`,
`auctions`.`auction_enabled`,
`auctions`.`auction_unixtime_expiration`,
`auctions`.`auction_belongs_to_hotel`,
`auctions`.`auction_seo_title`,
`auctions`.`auction_title`,
`auctions`.`auction_description_1`
FROM `bids`
LEFT JOIN `auctions` ON `auctions`.`auction_id`=`bids`.`bid_belongs_to_auction`
WHERE `auction_enabled`='1' AND `auction_unixtime_expiration` > '$time' AND `bid_from_user`='$userId'
AND EXISTS (
SELECT 1
FROM bids x
WHERE x.bid_belongs_to_auction = bids.bid_belongs_to_auction
AND x.bid_price > bids.bid_price
AND x.bid_from_user <> bids.bid_from_user
)
GROUP BY `bid_belongs_to_auction`
) AS X
WHERE `bid_from_user`='$userId'
";
最佳答案
这是一种不同的方法:
$query = "
SELECT
`max_bids`.`bid_belongs_to_auction`,
`auctions`.`auction_unixtime_expiration`,
`auctions`.`auction_belongs_to_hotel`,
`auctions`.`auction_seo_title`,
`auctions`.`auction_title`,
`auctions`.`auction_description_1`
FROM `auctions`
INNER JOIN (
SELECT
`bid_belongs_to_auction`,
MAX(`bid_price`) AS `auction_max_bid`,
MAX(CASE `bid_from_user` WHEN '$userId' THEN `bid_price` END) AS `user_max_bid`
FROM `bids`
GROUP BY `bid_belongs_to_auction`
) AS `max_bids` ON `auctions`.`auction_id` = `max_bids`.`bid_belongs_to_auction`
WHERE `auctions`.`auction_enabled`='1'
AND `auctions`.`auction_unixtime_expiration` > '$time'
AND `max_bids`.`user_max_bid` IS NOT NULL
AND `max_bids`.`user_max_bid` <> `max_bids`.`auction_max_bid`
";
基本上,当您检索所有拍卖的最高出价时,您也会同时检索特定用户的最高出价。下一步是将获得的列表加入到 auctions
中。表并在用户的最高出价不等于拍卖的最高出价时应用额外的过滤器。
注:`max_bids`.`user_max_bid` IS NOT NULL
条件可能是不必要的。在 SQL Server 中肯定会如此,因为 `max_bids`.`user_max_bid` <> `max_bids`.`auction_max_bid`
暗示了非空性。健康)状况。我不确定它在 MySQL 中是否相同。
关于sql - 如何修复此返回不正确值的 SQL 查询?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6277707/