返回购买 prod_id 为 BR01 的产品的所有顾客的电_牛客题霸

你想知道订购 BR01 产品的日期，有表OrderItems代表订单商品信息表，prod_id为产品id；Orders表代表订单表有cust_id代表顾客id和订单日期order_date；Customers表含有cust_email 顾客邮件和cust_id顾客id OrderItems表 prod_id order_num BR01 a0001 BR01 a0002 BR02 a0003 BR02 a0013 Orders表 order_num cust_id order_date a0001 cust10 2022-01-01 00:00:00 a0002 cust1 2022-01-01 00:01:00 a0003 cust1 2022-01-02 00:00:00 a0013 cust2 2022-01-01 00:20:00 Customers表代表顾客信息，cust_id为顾客id，cust_email为顾客email 【问题】返回购买 prod_id 为BR01 的产品的所有顾客的电子邮件（Customers 表中的 cust_email），结果无需排序。提示：这涉及 SELECT 语句，最内层的从 OrderItems 表返回 order_num，中间的从 Customers 表返回 cust_id。【示例结果】返回顾客email cust_email cust_email cust10@cust.com cust1@cust.com 【示例解析】产品id为BR01的订单a0001和a002的下单顾客cust10和cust1的顾客email cust_email分别是：cust10@cust.com 、cust1@cust.com

示例1

输入

DROP TABLE IF EXISTS `OrderItems`;
  CREATE TABLE IF NOT EXISTS `OrderItems`(
    prod_id VARCHAR(255) NOT NULL COMMENT '产品id',
    order_num VARCHAR(255) NOT NULL COMMENT '商品订单号'
  );
  INSERT `OrderItems` VALUES ('BR01','a0001'),('BR01','a0002'),('BR02','a0003'),('BR02','a0013');

  DROP TABLE IF EXISTS `Orders`;
  CREATE TABLE IF NOT EXISTS `Orders`(
    order_num VARCHAR(255) NOT NULL COMMENT '商品订单号',
    cust_id VARCHAR(255) NOT NULL COMMENT '顾客id',
    order_date TIMESTAMP NOT NULL COMMENT '下单时间'
  );
  INSERT `Orders` VALUES ('a0001','cust10','2022-01-01 00:00:00'),('a0002','cust1','2022-01-01 00:01:00'),('a0003','cust1','2022-01-02 00:00:00'),('a0013','cust2','2022-01-01 00:20:00');

DROP TABLE IF EXISTS `Customers`;
CREATE TABLE IF NOT EXISTS `Customers`(
    cust_id VARCHAR(255) NOT NULL COMMENT '顾客id',
    cust_email VARCHAR(255) NOT NULL COMMENT '顾客email'
  );
INSERT `Customers` VALUES ('cust10','cust10@cust.com'),('cust1','cust1@cust.com'),('cust2','cust2@cust.com');

输出

cust10@cust.com
cust1@cust.com