仅返回每个联接的顶行

Question

这是我目前的查询：

SELECT 
    u.UserName, s.StatusName
FROM 
    UserStatus us
    JOIN Status s on s.StatusId = us.StatusID
    JOIN Users u on u.UserId = us.UserId
WHERE 
    us.UserId in (select UserId from Users)
    AND us.DateCreated > '2017-07-14 00:00:00.000'
ORDER BY 
    us.DateCreated desc

它返回：

我如何才能获得每个用户的最新状态？

修改

我不能SELECT TOP 2，因为我不知道会有多少用户。可能有500个。可能有10个。

Answer 1

您可以在创建日期的位置设置每个用户的最大值 喜欢这个

SELECT 
    u.UserName, s.StatusName
FROM 
   UserStatus us
    JOIN Status s on s.StatusId = us.StatusID
    JOIN Users u on u.UserId = us.UserId
WHERE 
    us.UserId in (select UserId from Users)
    AND us.DateCreated = (SELECT MAX(DateCreated) FROM UserStatus us2 WHERE 
 us2.UserId = us.UserId)
ORDER BY 
    us.DateCreated desc 

Answer 2

尝试更改

SELECT u.UserName, s.StatusName

到

SELECT TOP(2) u.UserName, s.StatusName

那应该只选择前两行！ 见https://www.w3schools.com/sql/sql_top.asp

编辑：如果顶行更改，可以根据总状态的百分比进行选择