Leetcode Mysql 1398. 购买了产品 A 和产品 B 却没有购买产品 C 的顾客（DAY 7）

原题题目

代码实现（首刷自解）

# Write your MySQL query statement below
SELECT
DISTINCT c.customer_id,c.customer_name
FROMcustomers c
JOIN orders o
WHEREc.customer_id = o.customer_idand  exists (SELECT * FROM orders WHERE product_name = 'A' and customer_id = o.customer_id)and  exists (SELECT * FROM orders WHERE product_name = 'B' and customer_id = o.customer_id)and  not exists(SELECT * FROM orders WHERE product_name = 'C' and customer_id = o.customer_id)

代码实现（首刷优化）

# Write your MySQL query statement below
SELECT
DISTINCT c.customer_id,c.customer_name
FROMcustomers c JOIN orders o on c.customer_id = o.customer_id
GROUP BYo.customer_id
HAVINGSUM(product_name = 'A') > 0 and SUM(product_name = 'B') > 0 and SUM(product_name = 'C') = 0