Question

我有4张桌子，照片，标签，photos_tags和访问。

我必须选择前30张照片，这些照片应按照访问表中系数总和获得的因子排序。

我正在尝试此查询，但它没有说“每个派生表必须有一个别名”

    SELECT * FROM (
        SELECT *, (SELECT SUM(count) FROM (SELECT * FROM visits AS Visits WHERE Visits.tag_id IN (
                    SELECT tag_id FROM photos_tags AS PhotosTags WHERE PhotosTags.photo_id = Photo.id
                )))
            ) AS computed FROM photos AS Photo WHERE Photo.id NOT IN (

        ) ORDER BY computed LIMIT 30
    ) ORDER BY RAND()

编辑：查询我正在尝试抛出＃1064 - 您的SQL语法出错了;检查与MySQL服务器版本对应的手册，以便在''附近使用正确的语法.AS Table2 ORDER BY计算LIMIT 30 ）如表3第10行的ORDER BY RAND（）'

SELECT * FROM (
    SELECT *, (
        SELECT SUM(Table1.count) FROM (
            SELECT * FROM visits AS Visits WHERE Visits.tag_id IN (
                SELECT tag_id FROM photos_tags AS PhotosTags WHERE PhotosTags.photo_id = Photo.id
            )
        ) AS Table1
    ) AS computed FROM photos AS Photo WHERE Photo.id NOT IN (

    ) AS Table2 ORDER BY computed LIMIT 30
) AS Table3 ORDER BY RAND()

EDIT2 查询引发＃1054 - 'where子句'中的未知列'Photo.id'

SELECT * FROM (
    SELECT *, (
        SELECT SUM(Table1.count) FROM (
            SELECT * FROM visits AS Visits WHERE Visits.tag_id IN (
                SELECT tag_id FROM photos_tags AS PhotosTags WHERE PhotosTags.photo_id = Photo.id
            )
        ) AS Table1
    ) AS computed FROM photos AS Photo WHERE photos.id NOT IN (
 1,2
    ) ORDER BY computed LIMIT 30
) AS Table3 ORDER BY RAND()

Answer 1

我认为这是您想要的查询：

SELECT *
FROM (SELECT p.*, computed
      FROM Photos AS p
      LEFT JOIN (SELECT pt.photo_id, SUM(count) total
                 FROM photos_tags pt
                 JOIN visits v
                 ON v.tag_id = pt.tag_id
                 GROUP BY photo_id) AS pt
      ON p.id = pt.photo_id
      where p.id NOT IN ( )
      ORDER BY computed
      LIMIT 30) AS t1
ORDER BY RAND()

MySQL - 通过hABTM对相关列进行moltipired获得的因子排序

1 个答案: