1045. 买下所有产品的客户 难度：中等

1、题目描述

来源：力扣（LeetCode）

2、解题思路

1# 首先对Customer去重，select distinct * from customer
2# 然后，统计每个客人购买的货物种类数量select customer_id,count(product_key) cou1
3# 增加子表，对Product统计所有货物种类select count(*) as cou2 from Product
4# 对比两个量

3、提交记录

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