SQL：跨产品

Question

我试图确定有多少人购买了可以存在的所有不同产品对中的一对商品。例如。我有三种产品，A，B，C和我想确定有多少％的客户在每个国家/地区拥有两种产品的客户数量中购买了A和B，B和C以及A​​和C。

我的表格如下所示。

Customer | Country | Product 
1  | US | A 
1  | US | B 
2  | CA | A 
2  | CA | C 
3  | US | A 
3  | US | C 
4  | US | B 
5  | US | A 

请注意，客户只能属于一个国家。

我的期望的输出是：

Country | Pair | % 
US  | A_B | 25%  
US  | B_C | 0% 
US  | A_C | 25% 
CA  | A_B | 0%  
CA  | B_C | 0% 
CA  | A_C | 100% 

的％基本上是比

(# of unique customers who bought Product1 and Product2)/ 
(# of unique customers who bought Product1 or Product2) 

由国家。

因此，例如，在美国A_B我们有4个谁买了这些A或B但只买了1两A和B所以比1/4客户。

有没有一个很好的解决方案，如果我有一个大数目，任意数量的配对可以扩展？

Answer 1

如果你只是想有一个产品对，你可以用一个简单的join：

select t1.product, t2.product, count(distinct customer) 
from t t1 join 
    t t2 
    on t1.customer = t2.customer 
group by t1.product, t2.product; 

对于所有对，您可以将其用作子查询，然后返回到所有产品对的列表：

with pp as (
     select t1.product as product1, t2.product as product2, count(distinct customer) as cnt 
     from t t1 join 
      t t2 
      on t1.customer = t2.customer 
     group by t1.product, t2.product 
    ) 
select p1.product, p2.product, pp.cnt 
from (select distinct product from t) p1 cross join 
    (select distinct product from t) p2 left join 
    pp 
    on pp.product1 = t1.product and pp.product2 = t2.product; 

Answer 2

首先，使用JOIN得到Product的所有配对。然后使用APPLY来COUNT的Customer小号谁既带来了Product：

WITH CteProduct AS(
    SELECT DISTINCT 
     Prod1 = t1.Product, 
     Prod2 = t2.Product 
    FROM tbl t1 
    INNER JOIN tbl t2 
     ON t1.Product < t2.Product 
) 
SELECT 
    Parir = c.Prod1 + '_' + c.Prod2, 
    Number = ISNULL(x.Number, 0) 
FROM CteProduct c 
OUTER APPLY(
    SELECT 
     t.Customer, 
     Number = COUNT(DISTINCT t.Country) 
    FROM tbl t 
    WHERE t.Product IN(c.Prod1, c.Prod2) 
    GROUP BY t.Customer 
    HAVING COUNT(DISTINCT t.Product) = 2 

) x; 

ONLINE DEMO