获得前 10 个 post 和每个 post sql 的 10 个评论

Question

我想根据分数获得前 10 post，每个 post 获得 10 条评论。我正在使用以下查询：

with a as ( SELECt TOP 10  Score,Post.ID as PostID 
FROM            Post 
order by Score desc ), b as
(select  PostID,ID as CommentID from PostComment) 
select * from a
left join b
on b.PostID = a.PostID

此查询获得前 10 个 post，但问题是它获得了此 post 的所有评论。如何修改此查询以使每个 post?

仅获得 10 条评论

Answer 1

按照这些思路行事。

with a as 
(
    SELECt TOP 10  Score
    , Post.ID as PostID 
    FROM Post 
    order by Score desc 
), b as
(
    select PostID
    , ID as CommentID 
    , ROW_NUMBER() over (partition by PostID order by ID) as RowNum
    from PostComment
) 
select * 
from a
left join b
on b.PostID = a.PostID
where b.RowNum <= 10

Answer 2

SELECT
    *
FROM
    (
      SELECT
        Score ,
        Post.ID AS PostID ,
        ROW_NUMBER() OVER ( PARTITION BY p.id ) row_num ,
        comms.*
      FROM
        Post p
        OUTER APPLY (
                      SELECT TOP 10
                        pc.Comment_PostID ,
                        pc.ID AS CommentID
                      FROM
                        PostComment pc
                      WHERE
                        pc.postid = p.id
                    ) comms
    ) a
WHERE
    row_num < 11

Answer 3

试试这个：

WITH a AS ( 
    SELECT TOP 10
        Score ,
        Post.ID AS PostID
    FROM Post
    ORDER BY Score DESC
)
SELECT  *
FROM    a
OUTER APPLY ( 
    SELECT TOP 10
        pc.PostID ,
        pc.ID AS CommentID
    FROM      PostComment pc
    WHERE     pc.PostID = a.PostID
    --ORDER BY SomeColumn
) o

获得前 10 个 post 和每个 post sql 的 10 个评论

get top 10 posts and 10 comments for each post sql

sql

tsql

sql-server

sql-server-2012