[英]Sort a MySQL result based on total count of another result
我有表tbl_posts
和tbl_comments
,主键分别为post_id
和comment_id
。 我试过这段代码:
$allPosts=mysql_query("
select c.comment_id, post_id, count(*)
from post u,
comments c
where u.comment_id = c.comment_id
group by comment_id, post_id
LIMIT 10
");
但我不知道它的作用。 如何组合两个表,以便总评论确定tbl_posts
列出的帖子的tbl_posts
?
试试这个,如果你将每行分开并使用连接,它会更具可读性
select c.comment_id, post_id, count(*)
from post u join comments c
on u.comment_id = c.comment_id
group by comment_id, post_id LIMIT 10
看起来您有名为tbl_comment和tbl_post的表,但您的查询将它们列为仅发表评论和发布 。
select c.comment_id, post_id, count(*)
from tbl_post u, tbl_comments c
where u.comment_id = c.comment_id
group by comment_id, post_id LIMIT 10
$allPosts=mysql_query("select c.comment_id, post_id, count(*) from tbl_post u, tbl_comments c where u.comment_id = c.comment_id group by comment_id, post_id LIMIT 10");
这只是修复了查询以便它运行,并且没有解决您可能遇到的任何内容问题,即两者(我猜的是)的主要组是主键。
**编辑**要修复排序尝试:
SELECT tbl_post.comment_id, count(*)
FROM tbl_post, tbl_comments
WHERE tbl_post.comment_id = tbl_comment.comment_id
GROUP BY comment_id LIMIT 10
ORDER BY count(*)
SQL的解释:
您正在从表注释中选择列comment_id ,使用内部联接从表发布中选择post_id列,通过comment_id , post_id进行分组,限制为10个结果。
我会尝试:
$allPosts = mysql_query("SELECT * FROM
(SELECT c.comment_id, u.post_id, COUNT(*) AS 'count' FROM post u
LEFT JOIN comments c ON c.comment_id = u.comment_id
GROUP BY c.comment_id, u.post_id)
ORDER BY count DESC LIMIT 10");
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