[코트카타 105]

Customers Who Bought All Products

 

 

(오답) 5,6 product_key를 다 산 customer_id ㅠㅠ 왜 안 나오지.

select customer_id

from customer_id in (select c.customer_id

                                 from customer c join product_key p on c.product_key = p.product_key

                                 where p.product_key = 5 or 6) a

 

 

 

(정답)

select customer_id

from customer

group by 1

having count(distinct product_key) = (select count(*) from product)

 

product_key 에 distinct 를 해야했다. 그리고 이어져야하니까  select count(*)랑 같아야함.