T-SQL Group出问题 [英] T-SQL Group by problem

问题描述

关于SQL的和函数我有问题



我有这样的原始数据：

Hi,
I have a problem regarding on sum function of SQL

I have a raw data like this :

Count	Date	Row
10	1/1/2013	1
10	1/2/2013	2
10	1/3/2013	3

现在我要总结一下：

Now i want this to sum up :

Sum Date
10  1/1/2013
20  1/2/2013
30  1/3/2013

这是我目前的疑问：

This is my current query :

declare @count int
declare @i int
set @i = 1
set @count = (select max(Row) from #test) -- equals to 3

while @i <= @count
begin
	select sum(Count) as SumCount
		, Date
	from #test
	where row between 1 and @i
	group by Date
	set @i = @i + 1
end

然而结果是这样的：

However the result was like this :

SumCount   Date
10	   1/1/2013
10	   1/2/2013
10	   1/3/2013

我发现这是我每个日期的分组问题，

请帮我解决这个问题！

I figured out that it was the grouping per Date that i was having the problem,
plese help me on this thanks!

推荐答案

你想要的是跑步总数。如果您使用此关键字搜索Google，则会找到多篇文章。

从这里开始更好：计算简单运行总计在SQL Server中 [ ^ ]，在这里： http：//www.sqlperformance .com / 2012/07 / t-sql-queries / running-totals [ ^ ]

请注意作者的表现和资源考虑因素。与您可能已经知道的命令式方法相比，它并不像看起来那么简单。

What you want is called "running total". If you search google with this keywords, you will find several articles.
Better start here: Calculating simple running totals in SQL Server[^], and here: http://www.sqlperformance.com/2012/07/t-sql-queries/running-totals[^]
Please note the performance and resource considerations made by the authors. It is not as straightforward as it looks compared with an imperative approach you might already know.

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