Question

我尝试获得每种最新和最低报价的产品清单

表格产品：

id | name

表格提供：

id | product_id | price | created | dealer_id

表格残留：

id | offer_id | status

我试过了：

SELECT * FROM product INNER JOIN 
    (
        SELECT offer.product_id , offer.price
        FROM offer 
        LEFT JOIN invalids 
        ON offer.id = invalids.offer_id 
        WHERE invalids.id IS NULL 
        GROUP BY offer.dealer_id
        ORDER BY offer.created DESC
    ) o 
ON o.product_id = product.id 
ORDER BY product.name

我尝试了一个带有此优惠价值的sqlfiddle http://sqlfiddle.com/#!9/32658/3：

(`id`, `price`, `dealer_id`, `product_id`, `created`)  
(1,12.60,1,1,'2015-05-17 08:44:45'),  
(2,13.00,1,1,'2015-08-17 08:44:45'),  
(3,20.00,1,1,'2015-08-17 08:45:30'),  
(4,10.00,1,1,'2015-08-17 08:45:46'),  
(5,4.00,2,1,'2015-05-17 08:44:11'),  
(6,11.00,2,1,'2015-08-17 08:44:46'),  
(7,5.00,2,1,'2015-08-17 08:45:31'),  
(9,110.00,2,2,'2015-08-17 08:46:58'),  
(10,11.00,2,2,'2015-08-17 08:47:12');

产品ID 1的预期价值为商品ID 7，价格为5.

我认为我必须意识到这些步骤：

按created订阅优惠，按dealer_id分组以获取最新条目
从第1步中获取结果并按价格订购以获得最低价格。
为所有产品制作

也许我必须在SELECT FROM offer和GROUP BY使用第二个ORDER BY，但如何从第一个（外部）选择中获取product_id？

Answer 1

此查询可以帮助您：

SELECT * 
FROM product
JOIN (
  SELECT product_id, min(price) as minPrice, max(created) as newestOffer 
  FROM offer
  WHERE id NOT IN (SELECT offer_id FROM invalids)
  GROUP BY 1
) as b
ON product.id = b.product_id

Answer 2

那么我首先要获得每个产品的最新日期：

SELECT product_id, MAX(created) AS latestOffer
FROM offer
GROUP BY product_id;

完成后，您可以将其加入原始表格以获得该优惠：

SELECT o.*
FROM offer o
JOIN(
   SELECT product_id, MAX(created) AS latestOffer
   FROM offer
   GROUP BY product_id) tmp ON tmp.product_id = o.product_id AND tmp.latestOffer = o.created;

这是一个SQL Fiddle示例。

Answer 3

根据我的理解，在黑暗中拍摄......

许多嵌套的子查询..继续思考，必须有更好的方法......

SELECT OO.ID, OO.Price, OO.Dealer_Id, OO.Product_ID, OO.created, P.name 
FROM Offer OO
INNER JOIN (
  SELECT Min(Price) as MinP
  FROM offer O
  INNER JOIN (
    SELECT max(OI.created) as LatestOffer, OI.Dealer_ID, OI.Product_ID 
    FROM  Offer OI
    LEFT JOIN invalids I
     on OI.Id = I.offer_Id
    WHERE I.ID is null
    GROUP BY OI.Dealer_Id, OI.Product_Id
   ) B
   on O.Dealer_Id = B.Dealer_Id
  and O.Product_Id = B.Product_Id
  and O.Created = B.LatestOffer
  ) Z
 on OO.Price = Z.MinP
INNER JOIN product P 
 on P.ID = OO.Product_ID

SQL FIDDLE

从两个组之前的两个顺序中选择3个表

3 个答案: