Question

我有两张桌子：

UserTable包含（UserID，UserName）和StoryTable （StoryID，UserID（foreignkey），StoryName，InsertedDate）

如何查询每个用户名以及他发布的最新故事名称？（我很擅长查询这么好的借口，如果它非常基本的话）

我试过了：

选择a.Username，b.StoryName FROM [dbo]。[UserTable]作为INNER JOIN [dbo]。[StoryTable] as b ON a.UserID = b.UserID WHERE InsertedDate = MAX（InsertedDate）组由a.UserName;
组成

但它在sql server 2008中抛出错误。

Answer 1

将您的查询更改为：

SELECT a.Username, b.StoryName 
FROM [dbo].[UserTable] as A 
INNER JOIN [dbo].[StoryTable] as b ON a.UserID = b.UserID 
WHERE b.InsertedDate = 
      (SELECT MAX(InsertedDate) FROM [StoryTable] AS z WHERE z.UserID = A.UserID)

根据评论编辑：

SELECT a.Username, b.StoryName 
FROM [dbo].[UserTable] as A 
INNER JOIN [dbo].[StoryTable] as b ON a.UserID = b.UserID 
WHERE b.StoryID = 
      (SELECT MAX(z.StoryID) FROM [StoryTable] AS z WHERE z.UserID = A.UserID)

Answer 2

SELECT Top 1 a.Username, b.StoryName 
FROM [dbo].[UserTable] as A 
INNER JOIN [dbo].[StoryTable] as b ON a.UserID = b.UserID 
order by b.InsertedDate desc

Answer 3

你可以这样做

SELECT       u.Username, s.StoryName
FROM         [dbo].[UserTable] AS u
CROSS APPLY  (SELECT TOP 1 StoryName  
              FROM         [dbo].[StoryTable] AS ss
              WHERE        ss.UserID = u.UserID 
              ORDER BY     ss.InsertedDate DESC
             ) AS s

Answer 4

MAX是一个聚合函数，要使用聚合函数进行过滤，需要使用HAVING关键字而不是WHERE

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