滿足某些條件時的第一個日期

Question

我試圖在條件滿足時找到第一個日期。因此，邏輯是如下：

use 
[AdventureWorksDW2012] 
go 

;WITH sales AS (

select  d.OrderDateKey, 
     SalesAmount = SUM(d.SalesAmount) 
from  [dbo].[FactInternetSales] d 
group by d.OrderDateKey 
having  SUM(d.SalesAmount)>10000 
) 

select FirstOrderDateKey = MIN(OrderDateKey) 

from sales 

唯一的問題是，在我的數據是過於複雜和龐大，爲每個日期計算的值，然後選擇當條件滿足時敏時間。當互聯網銷售額超過10000時，有沒有快速找到第一次約會的方法？是否需要某種循環？

Answer 1

你也可以在單個語句中完成。如果您在orderdatekey上有適當的索引，則可以使用此功能提高性能。

select  MIN(s.OrderDateKey) as FirstOrderDateKey 
from  [dbo].[FactInternetSales] d 
group by d.OrderDateKey 
having  SUM(d.SalesAmount)>10000 

Answer 2

SELECT TOP 1 
     d.OrderDateKey 
     ,S.RunningTotal 
FROM [dbo].[FactInternetSales] d 
      CROSS APPLY (SELECT SUM(SalesAmount) AS RunningTotal 
          FROM [dbo].[FactInternetSales] 
          WHERE OrderDateKey <= d.OrderDateKey 
         ) S 
WHERE S.RunningTotal < -- Condition 
ORDER BY d.OrderDateKey DESC