php - (我的)带有 MAX 和 LEFT JOIN 的 SQL 查询

Question

我正在使用此查询:

SELECT `servers`.*, `sponsorships`.`sponsorship_id`, MAX(`sponsorships`.`bid`) as maxbid
                    FROM `sponsorships`
                    LEFT JOIN `servers`
                        ON `sponsorships`.`server_id` = `servers`.`id`
                    WHERE `sponsorships`.`impressions` <= '1000'
                    GROUP BY `sponsorships`.`server_id`
                    ORDER BY maxbid DESC
                    LIMIT 3;

这给了我以下内容

    [1] => Array
    (
        [id] => 23
        [user_id] => 1
        [cache_time] => 1395557635
        [sponsorship_id] => 1
        [maxbid] => 20
    )

但是 sponsorship_id => 1 的行不是具有 maxbid 的行。我需要做什么才能从 maxbid 中获取 sponsorship_id？

更新#1

我有这两个表:

赞助

服务器

我想要这个:

[1] => Array
(
    [id] => 23                       (servers.id)
    [user_id] => 1
    [cache_time] => 1395557635
    [sponsorship_id] => 3            (sponsorships.sponsorship_id) [see in the result from before I got sponsorship_id 1 and not 3 or 4 as it should be]
    [maxbid] => 20                   (MAX(`sponsorships`.`bid`))
)

因此，我当前遇到的问题是，我获得了最高出价，并且从赞助表中每台服务器仅获得一个条目，这正是我想要的。但我遇到的问题是 maxbid 来自 sponsorship_id 之外的另一行。那么，如何确保我从与 maxbid 同一行获取 sponsorship_id 呢？

Answer 1

我假设您希望在 LIMIT 3 中找到出价最高的前 3 个服务器。最好将服务器表放在连接的左侧，并使用双重嵌套查询来查找每个服务器的最高出价，并从赞助表中获取具有最高出价的 ID。

SELECT `servers`.*, c.`sponsorship_id`, c.`maxbidNQ` as maxbid
                    FROM `servers`
                    RIGHT JOIN (select `server_id`,`sponsorship_id`, MAX(`bid`) as maxbidNQ from (select * from `sponsorships` WHERE `impressions` <= '1000' ORDER BY `bid` desc) d GROUP BY `server_id`) c
                        ON c.`server_id` = `servers`.`id`
                    ORDER BY maxbid DESC
                    LIMIT 3;