如果你可以在Linq中做到這一點，總是可以在SQL中做一些事情嗎？

Question

我正在嘗試編寫一個應該像下面的Linq查詢一樣運行的SQL語句。主要是，我想根據一定的條件（Type ==「Check」）將兩列（現金和支票）列出一列（值*數量）。因此，如果類型是「檢查」，則將該值放入「檢查」列中，否則將其放入「現金」列中。

的Linq：

from ac in m_DataContext.acquisitions 
join ai in m_DataContext.acquireditems on ac.Identifier equals ai.AcquisitionIdentifier 
group ai by ac.SessionIdentifier into g 
select new 
{ 
    SessionIdentifier = g.Key, 
    Cash = g.Where(ai => ai.Type != "Check").Sum(ai => (double?)ai.Value * (int?)ai.Quantity) ?? 0, 
    Check = g.Where(ai => ai.Type == "Check").Sum(ai => (double?)ai.Value * (int?)ai.Quantity) ?? 0, 
    CheckQuantity = g.Where(ai => ai.Type == "Check").Sum(ai => (int?)ai.Quantity) ?? 0 
}; 

SQL：

SELECT a.SessionIdentifier, a.Checks as CheckQuantity, ???? as Cash, ???? as Check 
FROM Acquisitions ac 
INNER JOIN AcquiredItems ai ON ai.AcquisitionIdentifier = ac.Identifier 
GROUP BY a.SessionIdentifier 

這可能嗎？

Answer 1

你可以這樣說：

select sum(case when type = 'cash' then Value * Quantity else 0 end) as Cash, 
    sum(case when type = 'check' then Value * Quantity else 0 end) as Check 
from ...