力扣高频SQL 50题（基础版）第八题

1581. 进店却未进行过交易的顾客

题目说明

表：Visits

±------------±--------+

| Column Name | Type |

±------------±--------+

| visit_id | int |

| customer_id | int |

±------------±--------+

visit_id 是该表中具有唯一值的列。

该表包含有关光临过购物中心的顾客的信息。

表：Transactions

±---------------±--------+

| Column Name | Type |

±---------------±--------+

| transaction_id | int |

| visit_id | int |

| amount | int |

±---------------±--------+

transaction_id 是该表中具有唯一值的列。

此表包含 visit_id 期间进行的交易的信息。

有一些顾客可能光顾了购物中心但没有进行交易。请你编写一个解决方案，来查找这些顾客的 ID ，以及他们只光顾不交易的次数。

返回以 任何顺序 排序的结果表。

思路分析

本题利用子查询的方法结合逻辑查询not解题，首先在表Transactions中查出光顾且消费的顾客ID，然后在表Visits中过滤掉消费的顾客ID，即可得到进店却为进行交易的顾客，最后通过count函数统计次数。

实现过程

准备数据：

Create table If Not Exists Visits(visit_id int, customer_id int)
Create table If Not Exists Transactions(transaction_id int, visit_id int, amount int)
Truncate table Visits
insert into Visits (visit_id, customer_id) values ('1', '23')
insert into Visits (visit_id, customer_id) values ('2', '9')
insert into Visits (visit_id, customer_id) values ('4', '30')
insert into Visits (visit_id, customer_id) values ('5', '54')
insert into Visits (visit_id, customer_id) values ('6', '96')
insert into Visits (visit_id, customer_id) values ('7', '54')
insert into Visits (visit_id, customer_id) values ('8', '54')
Truncate table Transactions
insert into Transactions (transaction_id, visit_id, amount) values ('2', '5', '310')
insert into Transactions (transaction_id, visit_id, amount) values ('3', '5', '300')
insert into Transactions (transaction_id, visit_id, amount) values ('9', '5', '200')
insert into Transactions (transaction_id, visit_id, amount) values ('12', '1', '910')
insert into Transactions (transaction_id, visit_id, amount) values ('13', '2', '970')

实现方式：

select customer_id,count(customer_id) count_no_trans from Visits where visit_id not in (select visit_id from Transactions) group by customer_id;

结果截图：

总结：

#逻辑查询not
#查询不是河南的学生
select * from stu where address not in ('河南')