根据每个项目的最新交易日期选择数据

Question

我有一个查询，希望它列出每个库存项目的所有最新交易价格。我尝试使用MAX()列出每个商品的所有最新交易，但不包括价格，它可以工作，但是当我包括价格时，该方法将不起作用。

这是我的查询

SELECT MAX(DocDate) AS DocDate, StockCode, Price
FROM StockPurchasePriceHistory spph
INNER JOIN Stocks s
ON spph.Stock = s.Id
GROUP BY StockCode, Price
ORDER BY StockCode ASC

输出

Answer 1

使用row_number

select * from (SELECT row_number()over(partition by StockCode order by DocDate desc) rn
 , StockCode, Price
FROM StockPurchasePriceHistory spph
INNER JOIN Stocks s
ON spph.Stock = s.Id
) a where a.rn=1

Answer 2

尝试一下：

SELECT MAX(DocDate) AS DocDate, StockCode, sum(Price) as Price
FROM StockPurchasePriceHistory spph
INNER JOIN Stocks s
ON spph.Stock = s.Id
GROUP BY StockCode
ORDER BY StockCode ASC

Answer 3

这是使用APPLY的好地方：

SELECT spph.DocDate, s.StockCode, spph.Price
FROM Stocks s CROSS APPLY
     (SELECT TOP (1) spph.*
      FROM StockPurchasePriceHistory spph
      WHERE spph.Stock = s.Id
      ORDER BY spph.DocDate DESC
     ) spph;

有了StockPurchasePriceHistory(Stock, DocDate desc)上的索引，我希望它会比使用窗口函数的替代方法快一点，并且与相关子查询的速度差不多。