Mysql 从联接表中仅获取3行

我试图从联接表中仅获取三行。 例如，我有一个categories表。我想在不使用SQL内部循环的情况下从这些类别中获得流行类别和3篇文章。职位总数应为12

我试过了，但没用。如果我设置限制1，它就可以工作。但不在限制3上工作

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您的子查询返回多条记录，实际上是3，因此应将相等运算符替换为IN运算符

考虑：

SELECT 
    categories.name AS cname,
    categories.url  AS curl,
    articles.name,
    articles.url,
    articles.image
FROM   
    categories
    JOIN articles ON articles.id IN (
        SELECT p.id
        FROM articles AS p
        WHERE categories.id = p.category AND p.delete = '0'
        ORDER  BY p.id DESC
        LIMIT  3
    )
WHERE  
    categories.delete = '0'
    AND categories.popular = '1'

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在MySQL 8+中，您只需执行以下操作：

SELECT c.name AS cname, c.url  AS curl,
       a.name, a.url, a.image
FROM categories c JOIN
     (SELECT a.*,
             ROW_NUMBER() OVER (PARTITION BY a.category ORDER BY a.id DESC) as seqnum
      FROM articles a
      WHERE a.delete = 0
     ) a
     ON a.category = c.id
WHERE a.seqnum <= 3 AND
      c.delete = 0 AND
      c.popular = 1

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将您的语法JOIN articles ON articles.id=替换为JOIN articles ON articles.id IN not worked for me:/可能重复我在phpmyadmin:1235中遇到的错误-此版本的MySQL尚不支持“LIMIT&IN/ALL/ANY/SOME subquery”@Cihan:您使用的是哪个版本的MySQL？

SELECT c.name AS cname, c.url  AS curl,
       a.name, a.url, a.image
FROM categories c JOIN
     (SELECT a.*,
             ROW_NUMBER() OVER (PARTITION BY a.category ORDER BY a.id DESC) as seqnum
      FROM articles a
      WHERE a.delete = 0
     ) a
     ON a.category = c.id
WHERE a.seqnum <= 3 AND
      c.delete = 0 AND
      c.popular = 1