大多数匹配标记的SQL查询

让我们想象一下抽象数据库，它包含带有附加标记的对象（默认多对多关系和附加表）。现在，我们有一个用户，他希望找到与他提供的大多数标记相匹配的对象，并按相关性排序。例如：

Object1: TagA, TagB, TagC, TagD
Object2: TagA,       TagC, TagD
Object3: TagB,             TagD, TagE, TagF
Object4: TagA, TagB, TagC,       TagE

用户要求标记B、标记C、标记D 预期结果应如下所示：

Object1 (3 matches)
Object4 (2 matches)
Object2 (2 matches)
Object3 (1 match)

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编辑：示例结构（我在SQLite中创建了它，但我们可以安全地假设MSSql）

预期结果（对于查询“TagB、TagC、TagD”）：

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不确定您的表结构，但从您的帖子来看，您可以使用

groupby

来实现类似的功能

select object, count(tag) as tagcount
from tags
where tag in ('TagB', 'TagC', 'TagD')
group by object;

以下是答案：

SELECT t1.name, COUNT(t1.tag) as count FROM
    (SELECT o.Name as name, 
        1 as tag 
     FROM Objects AS o,
        ObjectTag AS ot 
     WHERE o.Id = ot.ObjectId 
         AND ot.TagId IN (2,3,4)) AS t1
     GROUP BY t1.name
     ORDER BY count DESC

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你能分享一下你的桌子结构吗？还有，你在用什么？

select object, count(tag) as tagcount
from tags
where tag in ('TagB', 'TagC', 'TagD')
group by object;

SELECT t1.name, COUNT(t1.tag) as count FROM
    (SELECT o.Name as name, 
        1 as tag 
     FROM Objects AS o,
        ObjectTag AS ot 
     WHERE o.Id = ot.ObjectId 
         AND ot.TagId IN (2,3,4)) AS t1
     GROUP BY t1.name
     ORDER BY count DESC