按更近的距离获取 MIN MAX 分组

Question

商店

id_shop | id_prod_ty |位置

和

产品

编号 |价格 | id_prod_ty |距离

table stores 包含 2 个商店，每个 id_prod_ty（产品类型）和一个位置。
表 products 包含许多不同价格和距离的记录

基本上我需要有一个查询，为每种产品以及按更接近的价格分组的每个商店（并且不接近其他商店）选择低价和高价

例如

商店

id_shop | id_prod_ty |位置 1 | 1 | 3 2 | 1 | 7 3 | 2 | 8 4 | 2 | 4 ……

产品

编号 |价格 | id_prod_ty |距离 1 | 10 | 1 | 1 2 | 04 | 1 | 2 3 | 02 | 1 | 4 4 | 44 | 1 | 2 5 | 09 | 1 | 1 6 | 13 | 1 | 7 7 | 15 | 1 | 8 8 | 09 | 2 | 5 9 | 12 | 2 | 8 10 | 17 | 2 | 1 11 | 32 | 2 | 13 12 | 22 | 2 | 2 ...

结果喊成这样

id_prod_ty | id_price_low | id_price_high | id_shop 1 | 3 (02) | 4 (44) | 1 1 | 6 (13) | 7 (15) | 2 2 | 8 (09) | 12 (22) | 4 2 | 9 (12) | 11 (32) | 3 ...

谢谢

Answer 1

我想我理解这个问题。对于每个价格，您都在尝试根据距离和位置分配最近的商店。

方法从加入职位和商店开始。然后它计算位置和距离之间的差异——这似乎是您正在使用的度量。每个价格 ID 将出现两次（每个商店一次）。它使用窗口函数计算每个 id 的最小差异。

有了这些信息，查询就可以确定哪个是最近的商店。此版本返回价格，而不是最低价格的 id。这是最终的、未经测试的查询：

select id_prod_ty,
       MIN(case when diff = minDiff then price) as price_low,
       MAX(case when diff = minDiff then price) as price_high,
       s.id_shop
from (select p.id_prod_ty,
             s.id_shop,
             p.price,
             (p.distance - s.position) as diff,
             MIN(p.distance - s.position) over (partition by p.id) as minDiff
      from products p join
           shops s
           on p.id_prod_ty = s.id_prod_ty
    ) ps
group by id_prod_ty, id_shop

这是一个获取 id 的变体。它使用窗口函数来查找最低和最高价格，然后将价格与这些值进行比较以获取 id：

select id_prod_ty,
       MIN(minPrice) as price_low,
       MIN(case when price = minPrice then id end) id_price_low,
       MAX(maxprice) as price_high,
       MIN(case when price = maxPrice then id end) id_price_high,
       id_shop
from (select *,
             MIN(IsThisShopPrice) over (partition by id_prod_ty, id_shop) as minPrice,
             MIN(IsThisShopPrice) over (partition by id_prod_ty, id_shop) as maxPrice,
      from (select p.id_prod_ty, s.id_shop, p.price, p.id,
                   (p.distance - s.position) as diff,
                   (case when (p.distance - s.position) = MIN(p.distance - s.position) over (partition by p.id)
                         then 'Y'
                         else 'N'
                    end) as IsThisShop
                   (case when (p.distance - s.position) = MIN(p.distance - s.position) over (partition by p.id)
                         then price
                    end) as IsThisShopPrice
            from products p join
                 shops s
                 on p.id_prod_ty = s.id_prod_ty
           ) ps
    ) ps
group by id_prod_ty, id_shop