选择从分组查询中输入的总和

Question

我需要做一个查询，根据用户输入条件从表中选择一个分组的行集合，然后在select中，我将从行子集中求和数据。

在一篇文章中描述这个设置是相当广泛的，所以这里用我能做到的最简单的方式来演示这个问题:

我们有这个表:DemoTable

<表类> ID StaticKey GroupKey 价值 tbody><<tr>12223B24B25C26C2

更简单:

select GroupKey,
sum(Value) as sum_of_A,
sum(GroupKey='A') as count_of_A
from DemoTable
where GroupKey='A'  
group by  GroupKey;

https://dbfiddle.uk/sdYlTw57

不总是D.ID in (DT.ID)吗?

select 
DT.GroupKey,       
(select sum(D.Value) from DemoTable D where D.GroupKey = 'A') as 'Sum of A''s',
(select COUNT(D.ID) from DemoTable D where D.GroupKey = 'A')  as 'Count of A''s'
from DemoTable DT
group by DT.StaticKey;

它的工作，但可能是太简单了…

你也可以试试这个

SELECT DT.GroupKey,
SUM(DT.Value) AS 'Sum of A''s',
COUNT(DT.ID) AS 'Count of A''s'
FROM DemoTable DT
WHERE DT.GroupKey = 'A'
GROUP BY DT.StaticKey;