如何通过COUNT从我的SQL中的另一个表更新

Question

我使用此查询来更新作者发表的文章

UPDATE authors SET total_articles = 
(
SELECT COUNT(*) FROM articles 
WHERE articles.author_id=authors.author_id  
GROUP BY author_id
)

但是，当我添加其他WHERE子句以仅将已发布的文章计为

UPDATE authors SET published_articles = 
(
SELECT COUNT(*) FROM articles 
WHERE articles.author_id=authors.author_id AND articles.status='published' 
GROUP BY author_id
)

count(*)不能正确计算已发表文章的数量。

Answer 1

如果您更改查询如下所示该怎么办

UPDATE authors SET published_articles = 
(
SELECT COUNT(*) FROM articles a
JOIN authors au ON a.author_id = au.author_id 
WHERE a.status='published' 
GROUP BY a.author_id
)

Answer 2

这可能与您的数据内容有关，但是该关系可能基于子选择结果的联接

  UPDATE authors 
  INNER JOIN (
  SELECT articles.author_id , COUNT(*) as num 
  FROM articles 
  WHERE articles.author_id=authors.author_id 
  AND articles.status='published' 
  GROUP BY author_id
  ) t on t.author_id=authors.author_id 
  SET published_articles = t.num

Answer 3

尝试将UPDATE与JOIN ：

update authors a
join (
    select author_id,
        count(*) cnt
    from articles
    where status = 'published'
    group by author_id
    ) ar
    on ar.author_id = a.author_id
set a.total_articles = ar.cnt;

它在子查询中查找每个作者的已发布文章的已过滤计数，然后将其与author表联接以更新其列。