查询找到 2 件最便宜的商品，其总价值为 3000

Question

我有一张桌子产品：

ProductName          Price  
straight jeans       1500  
slim jeans           2500  
Denim jacket         3000  
Denim shorts         800  
Skinny jeans         1700  
loose Jeans          2100  
mom Jeans            2800  
wide jeans           1850  
distressed jeans     1100  
bootcut jeans        1350

如果购买了两件总价值超过 3000 的不同物品，他们会赠送第三件作为礼物。 我需要一个 SQL 查询，以在两件事上花费最少，并将第三作为最昂贵的。

我唯一想到的就是通过所有可能的组合到 go 并找到超过 3000 的最便宜的组合。

WITH Products_sum AS (
  SELECT p1.ProductName AS ProductName1, p2.ProductName AS ProductName2, p1.Price + p2.Price AS TotalPrice
  FROM products p1
  JOIN products p2
    ON p1.ProductName < p2.ProductName
)
SELECT top 1 ProductName1, ProductName2, TotalPrice
FROM Products_sum
WHERE TotalPrice >= 3000
order by TotalPrice asc

我期待这样的回答：

bootcut jeans        1350
Skinny jeans         1700
Denim jacket         3000

但是不知道该怎么做。

Answer 1

我从您离开的地方继续并编写了预期的结果。

转换为 cte 的顶级产品和最昂贵的产品。

将最终结果集与 union 语句结合起来。

WITH Products_sum AS (
  SELECT p1.ProductName AS ProductName1
    , p2.ProductName AS ProductName2
    , p1.Price + p2.Price AS TotalPrice
    , p1.Price Price1
    , p2.Price Price2
  FROM products p1
  JOIN products p2
    ON p1.ProductName < p2.ProductName
),
topProducts as (SELECT top 1 ProductName1, ProductName2, Price1, Price2
FROM Products_sum
WHERE TotalPrice >= 3000
order by TotalPrice asc),
moreExpensive as (
    select top 1 ProductName, Price
    from products 
    order by price desc
)
select productName, Price from(
select 1 as pos, ProductName1 ProductName, Price1 Price from topProducts
union
select 2, ProductName2 , Price2 from topProducts
union
select 3, ProductName, Price
from moreExpensive )q
order by pos

Answer 2

SELECT p1.ProductName, p1.Price,
       p2.ProductName, p2.Price,
       p3.ProductName, p3.Price
FROM Products p1
JOIN Products p2
on p1.ProductName < p2.ProductName
JOIN Products p3
ON p2.ProductName < p3.ProductName AND 
       p1.Price + p2.Price + p3.Price > 3000
LEFT JOIN Products nonexistent
ON NOT (nonexistent.ProductName IN (p1.ProductName, p2.ProductName, p3.ProductName)) AND
   p1.Price + p2.Price + nonexistent.Price > 3000 AND
   nonexistent.Price < p3.Price
WHERE nonexistent.ProductName IS NULL

我们

• select 每个 ( p1 , p2 , p3 ) 元组
• 他们的名字不同的地方
• 他们的价格大于3000
• 并且不存在任何与这三个不同的nonexistent的记录， p1和p2会产生比p3更小的价格，但仍高于 3000