Question

我有两个表，image和gradeReason。每张图片都会根据其质量获得评分，用户可以通过选择{{1}来选择4个不同的原因（reasonID_1，reasonID_2，reasonID_3，reasonID_4） }}。原因的细分存储在reasonID表中。

gradeReason

我想要的是一个查询，它将返回每个reasonID在审核中使用的次数以及gradeReason的名称

e.g。

审计125 -

reasonID 3被使用了两次 - 名字'患者感动'，

reasonID 2使用了两次 - 名称为“曝光不足”。

我会诚实地说，我已经挣扎了好几天，我甚至不知道从哪里开始。

Answer 1

这更难，因为您的数据未正确规范化。以下方法首先规范化数据，然后进行连接和聚合：

select ir.auditId, gr.ReasonId, gr.category, gr.name, count(*) as cnt
from (select i.imageID, i.auditID,
             (case when n.n = 1 then ReasonID_1
                   when n.n = 2 then ReasonID_2
                   when n.n = 3 then ReasonID_3
                   when n.n = 4 then ReasonID_4
              end) as ReasonId
      from image i cross join
           (select 1 as n union all select 2 union all select 3 union all select 4
           ) n
      ) ir join
      gradeReason gr
      on ir.ReasonId = gr.ReasonId
group by ir.auditId, gr.ReasonId, gr.category, gr.name
order by cnt desc;

Answer 2

对于您的选择，您必须为gradeReason的每个外键加入gradeReason：

    SELECT imageID
         , auditID
         , r1.name
         , r2.name
         , r3.name
         , r4.name
     FROM image i
LEFT JOIN gradeReason r1 on i.reasonID_1 = r1.reasonID
LEFT JOIN gradeReason r2 on i.reasonID_2 = r2.reasonID
LEFT JOIN gradeReason r3 on i.reasonID_3 = r3.reasonID
LEFT JOIN gradeReason r4 on i.reasonID_4 = r4.reasonID

你的示例数据不合理，因为你的桌面图片中gradeReason的外键不在gradeReason中，但我猜你还有更多的gradeRasons。

此外，您的结构未规范化： gradeReason在类别的行中有重复的条目。这不是太糟糕，但最好有一个单独的gradeReasonCategories表。

Answer 3

使用UNIONS的另一个选项： -

SELECT auditId, ReasonId, category, name, SUM(cnt)
FROM
(
    SELECT ir.auditId, gr.ReasonId, gr.category, gr.name, count(*) as cnt
    FROM image ir
    INNER JOIN gradeReason gr
    ON ir.reasonID_1 = gr.ReasonId
    WHERE ir.auditId = 123
    GROUP BY ir.auditId, gr.ReasonId, gr.category, gr.name
    UNION ALL
    SELECT ir.auditId, gr.ReasonId, gr.category, gr.name, count(*) as cnt
    FROM image ir
    INNER JOIN gradeReason gr
    ON ir.reasonID_2 = gr.ReasonId
    WHERE ir.auditId = 123
    GROUP BY ir.auditId, gr.ReasonId, gr.category, gr.name
    UNION ALL
    SELECT ir.auditId, gr.ReasonId, gr.category, gr.name, count(*) as cnt
    FROM image ir
    INNER JOIN gradeReason gr
    ON ir.reasonID_3 = gr.ReasonId
    WHERE ir.auditId = 123
    GROUP BY ir.auditId, gr.ReasonId, gr.category, gr.name
    UNION ALL
    SELECT ir.auditId, gr.ReasonId, gr.category, gr.name, count(*) as cnt
    FROM image ir
    INNER JOIN gradeReason gr
    ON ir.reasonID_4 = gr.ReasonId
    WHERE ir.auditId = 123
    GROUP BY ir.auditId, gr.ReasonId, gr.category, gr.name
) Sub1
GROUP BY auditId, ReasonId, category, name

挣扎着MySQL子查询

3 个答案: