sql-server - 有没有办法使用内连接更新 TOP (N)，其中 N 是此类内连接的字段？

Question

我正在尝试创建一个同步销售表和库存表的脚本。为此，我在库存表(每个库存项目有 1 条记录)上编写了更新，如下所示:

UPDATE TOP (q.QuantitySold) i
SET i.Converted = 1,
    i.CartID = q.CartID,
    i.ReservedDate = GETDATE()
FROM Inventory i
INNER JOIN
(
    SELECT product.ProductID, sales.CartID, COUNT(sales.ID) AS QuantitySold
    FROM Products product
    INNER JOIN Sales sales ON sales.ProductID = product.ProductID
    WHERE <conditions> 
    GROUP BY product.ProductID, sales.CartID
) q ON q.ProductID = i.ProductID
WHERE i.Converted = 0 AND i.CartID IS NULL 

但它不起作用，错误提示 q.QuantitySold 无法绑定(bind)。

有没有办法在不使用游标的情况下更新N条库存记录(等于销售数量)？我拒绝就这样放弃。

注意:这是实际查询的简化版本。

Answer 1

您可以使用ROW_NUMBER来枚举需要更新的库存项目。

WITH cteProducts AS(
    SELECT product.ProductID, sales.CartID, COUNT(sales.ID) AS QuantitySold
    FROM Products product
    INNER JOIN Sales sales ON sales.ProductID = product.ProductID
    WHERE <conditions> 
    GROUP BY product.ProductID, sales.CartID
),
cteInventory AS(
    SELECT *,
        ROW_NUMBER() OVER( PARTITION BY ProductID ORDER BY (SELECT NULL)) AS rn /*Change the ORDER BY for an actual column if needed, probably for FIFO*/
    FROM Inventory
    WHERE i.Converted = 0 
    AND i.CartID IS NULL 
)
UPDATE i
SET i.Converted = 1,
    i.CartID = q.CartID,
    i.ReservedDate = GETDATE()
FROM cteInventory i
INNER JOIN cteProducts q ON q.ProductID = i.ProductID
WHERE i.rn <= q.QuantitySold;