leetcode 1581.进店却未进行过交易的顾客

2023-12-24 37 阅读1分钟

左外连接, 然后寻找transaction_id为null的数据条数

select
    v.customer_id,
    count(v.customer_id) as count_no_trans
from
    Visits as v
left join
    Transactions as t
on v.visit_id = t.visit_id
where t.transaction_id is null
group by customer_id ;