Question

我有一个帖子表和postcontent表。

每次编辑帖子时，都会在postcontent表中添加一个条目。

在每个这样的时间，一个名为version的字段将增加1 在postcontent表中。

如何从post post和[Description]到postcontent表获取PostId 每个帖子的版本最大即按帖子ID分组即我希望每个帖子都有一个原始文件，这是帖子的“最大版本”

Answer 1

select P.PostID,
       PC.[Description]
from Post as P
inner join 
  (
    select PostID,
           [Description],
           row_number() over(partition by PostID order by [Version] desc) as rn
    from PostContent
  ) as PC
  on P.PostID = PC.PostID
where PC.rn = 1

Answer 2

我认为您将PostId表中的PostContent作为外键，并且您希望以最高版本检索所有postId。

select max(version),PostId from PostContent groupby PostId

Answer 3

SELECT 
    p.[PostID],
    pc.[Description]
FROM
    [Post] AS p
INNER JOIN
    [PostContent] AS pc
    on p.PostID = pc.PostID 
WHERE
    pc.[Version] = (SELECT MAX([Version]) FROM PostContent WHERE PostID = p.PostID)

使用group by和maximum

3 个答案: