博客

https://leetcode.cn/problems/customers-who-never-order/

使用in

select Name Customers from Customers where 
id not in (select CustomerId from Orders)

664 ms

加上disinct后速度快了很多

select Name Customers from Customers where 
id not in (select distinct CustomerId from Orders)

273 ms

使用exists

select Name Customers from Customers c where 
not exists (select distinct CustomerId from Orders o where o.CustomerId=c.Id)

271 ms

使用join

select c.Name Customers from Customers c 
left join Orders o on o.CustomerId=c.Id
where o.CustomerId is null

555ms