Question

\ d发布

                                   Table "public.posts"
   Column    |          Type          |                     Modifiers                      
-------------+------------------------+----------------------------------------------------
 id          | integer                | not null default nextval('posts_id_seq'::regclass)
 title       | character varying(100) | not null
 content     | character varying(500) | not null
 created_at  | date                   | 
 updated_at  | date                   | 
 tags        | character varying(55)  | not null default '50'::character varying
 category_id | integer                | not null default 1
Indexes:
    "posts_pkey" PRIMARY KEY, btree (id)

\ d comments

                                   Table "public.comments"
   Column   |          Type          |                       Modifiers                       
------------+------------------------+-------------------------------------------------------
 id         | integer                | not null default nextval('comments_id_seq'::regclass)
 post_id    | integer                | not null
 name       | character varying(255) | not null
 email      | character varying(255) | not null
 content    | character varying(500) | not null
 created_at | date                   | 
 updated_at | date                   | 
Indexes:
    "comments_pkey" PRIMARY KEY, btree (id)

我需要一个SQL查询来查找评论最多的帖子。我该怎么办？

Answer 1

在tsql中你会做到以下几点，我希望它能引导你朝正确的方向发展

SELECT
         p.id,
         c.postcount
    FROM posts as p
    INNER JOIN (
                  SELECT
                         post_id,
                         count(*) AS postcount
                  FROM comments
                  GROUP BY post_id
               ) as c
           on p.id = c.post_id

    Order by c.postcount desc

Answer 2

  SELECT id, title, comment_count
    FROM ( SELECT p.id, p.title, COUNT(c.id) AS comment_count
             FROM posts p
                 ,comments c
             WHERE c.post_id = p.id
             GROUP BY p.id, p.title
             ORDER BY 3 DESC ) x
    LIMIT 1;

需要一个SQL查询来查找注释编号/计数DESC的评论最多的帖子

2 个答案: