SQL where 子句有两个单独的值？

Question

所以对于一项任务，我需要从chinook 数据库中找到支持来自加拿大的客户的员工的经理

现在我有以下代码：

select distinct employee.LastName, employee.EmployeeId, employee.ReportsTo
from customer,
     employee
where customer.Country = 'Canada'
  and customer.SupportRepId = employee.EmployeeId;

所以我得到以下结果

所以我需要获取EmployeeId为2的总经理的姓名，但我不知道如何将其放入一个查询中。

这是所有员工的概述：

Answer 1

您必须两次加入员工表：

select distinct employee.LastName, employee.EmployeeId, manager.Lastname
from 
 customer 
 join     employee as employee on customer.SupportRepId = employee.EmployeeId
 join employee as manager on employee.ReportsTo = manager.employeeId
where customer.Country = 'Canada'