使用SUM运行总计的T-SQL

Question

我有一个简单的表,有一些虚拟数据设置,如:

|id|user|value|
---------------
 1  John   2
 2  Ted    1
 3  John   4
 4  Ted    2

我可以通过执行以下sql(MSSQL 2008)语句来选择运行总计:

SELECT a.id, a.user, a.value, SUM(b.value) AS total
FROM table a INNER JOIN table b
ON a.id >= b.id
AND a.user = b.user
GROUP BY a.id, a.user, a.value
ORDER BY a.id

这会给我的结果如下:

|id|user|value|total|
---------------------
 1  John   2     2
 3  John   4     6
 2  Ted    1     1
 4  Ted    2     3

现在是否可以只检索每个用户的最新行？结果将是:

|id|user|value|total|
---------------------
 3  John   4     6
 4  Ted    2     3

我是以正确的方式来做这件事的吗？任何建议或新的路径都会很棒!

Answer 1

不需要加入,您可以通过以下方式加快查询速度:

select id, [user], value, total
from
(
  select id, [user], value, 
  row_number() over (partition by [user] order by id desc) rn, 
  sum(value) over (partition by [user]) total
from users
) a
where rn = 1

Answer 2

试试这个:

;with cte as 
     (SELECT a.id, a.[user], a.value, SUM(b.value) AS total
    FROM users a INNER JOIN users b
    ON a.id >= b.id
    AND a.[user] = b.[user]
    GROUP BY a.id, a.[user], a.value
     ),
cte1 as (select *,ROW_NUMBER() over (partition by [user] 
                         order by total desc) as row_num
         from cte)
select  id,[user],value,total from cte1 where row_num=1

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