Question

我尝试了几种选择，但我找不到合适的解决方案。我想更新Products表中的两列。需要从另一个名为ProductShops的表中更新这些列。

这两列名为LowestPrice和LowestPriceShopId。因此，我需要来自NewPrice + DeliveryCosts中的总和ProductShops和来自该记录的ShopId的最低值。需要在Products表中进行更新。

我尝试过的事情是：

UPDATE Products 
SET LowestPrice = MIN(ps.NewPrice + ps.DeliveryCosts), 
LowestPriceShopId = ps.ShopId 
FROM Products 
INNER JOIN ProductShops ps ON Products.Id = ps.ProductId

错误消息：聚合可能不会出现在UPDATE语句的集合列表中。

UPDATE p 
SET LowestPrice = ps2.totalPrice,
LowestPriceShopId = ps2.ShopId
FROM Products p JOIN
(select ps.ProductId, MIN(ps.NewPrice + ps.DeliveryCosts) AS totalPrice, ShopId FROM ProductShops ps) ps2
ON p.Id = ps2.ProductId

错误消息：列'ProductShops.ProductId'在选择列表中无效，因为它不包含在聚合函数或GROUP BY子句中。

UPDATE Products
SET LowestPrice = (SELECT MIN(ps.NewPrice + ps.DeliveryCosts) 
FROM ProductShops ps WHERE ps.ProductId = p.Id)
FROM Products p

使用上一个查询，我不知道如何获取ShopId。

Answer 1

UPDATE p
SET LowestPrice = ps2.totalPrice,
    LowestPriceShopId = ps2.ShopId
FROM Products p
JOIN (SELECT
    ps.ProductId,
    MIN(ps.NewPrice + ps.DeliveryCosts) AS totalPrice,
    ShopId
FROM ProductShops ps
GROUP BY ps.ProductId,ShopId) ps2
    ON p.Id = ps2.ProductId

Answer 2

我找到了正确的解决方案：

UPDATE p 
SET LowestPrice = ps3.totalPrice,
LowestPriceShopId = ps3.ShopId
FROM Products p 
JOIN
(
SELECT ps1.ProductId, ps1.NewPrice + ps1.DeliveryCosts as totalPrice, ps1.ShopId FROM ProductShops ps1 
LEFT JOIN ProductShops ps2
ON ps1.ProductId = ps2.ProductId AND (ps1.NewPrice + ps1.DeliveryCosts) > (ps2.NewPrice + ps2.DeliveryCosts)
WHERE ps2.NewPrice is NULL AND ps2.DeliveryCosts is NULL
) ps3
ON p.Id = ps3.ProductId

Answer 3

您需要char：

GROUP BY

同时UPDATE p SET LowestPrice = ps2.totalPrice, LowestPriceShopId = ps2.ShopId FROM Products p JOIN ( select ps.ProductId, MIN(ps.NewPrice)+MIN(ps.DeliveryCosts) AS totalPrice, ShopId FROM ProductShops ps GROUP BY ps.ProductId, ps.ShopId ) ps2 ON p.Id = ps2.ProductId和ProductId

如何使用MSSQL中的聚合函数更新表中的两列？

3 个答案: