[문제풀이] Leet code - Customers Who Bought All Products

출처

 

문제

모든 제품을 구매한 고객의 id를 출력하라

문제에 대한 해석

제품번호 5,6번을 모두 구매한 고객 1,3번을 출력하는 것

풀이(MYSQL)

방법1.

select customer_id
from Customer
group by customer_id 
having group_concat(distinct(product_key) order by 1 ) = (select group_concat(product_key order by 1) from Product)

 

 

방법2. 

select customer_id 
from Customer
group by customer_id 
having count(distinct( product_key)) = (select count(distinct(Product_key)) from Product)