如何在SQL Server 2008中使用SUM編寫內部聯接查詢

Question

我有兩個查詢

SELECT PId,
       COUNT(*) AS Quantity
FROM Bill_Entry
GROUP BY PId
ORDER BY Quantity DESC

SELECT SUM(CAST(Quantity AS FLOAT)) AS TotalSalesQuantity,
       SUM(CAST(Total AS FLOAT)) AS TotalSalesAmount
FROM Bill_Entry
WHERE ProductId = pi

兩者都是同一張桌子。 如何加入這個查詢？

Answer 1

試試這個-

SELECT PId,
       MAX(TotalSalesQuantity),
       MAX(TotalSalesAmount),
       COUNT(*) AS Quantity
FROM (
    SELECT PId,
           SUM(CASE WHEN ProductId = @pi THEN Quantity * 1. END) OVER () AS TotalSalesQuantity,
           SUM(CASE WHEN ProductId = @pi THEN Total * 1. END) OVER () AS TotalSalesAmount
    FROM Bill_Entry
) t
GROUP BY PId
ORDER BY Quantity DESC