1045. 買下所有產品的客戶 難度：中等

1、題目描述

來源：力扣（LeetCode）

2、解題思路

1# 首先對Customer去重，select distinct * from customer
2# 然後，統計每個客人購買的貨物種類數量select customer_id,count(product_key) cou1
3# 增加子表，對Product統計所有貨物種類select count(*) as cou2 from Product
4# 對比兩個量

3、提交記錄

select customer_id
from

(select customer_id,count(product_key) cou1
from (select distinct * from customer)a3
group by customer_id) a,

(select count(*) as cou2
from Product)b
    
where a.cou1=b.cou2