Mysql SQL查询子查询结构

我在SQL方面遇到了问题。我已经创建了一个餐厅的数据库，我正在尝试创建一个查询，显示为同一客户服务的主管和员工

Employee

表具有

supervisor\u id

和

Employee\u id

。

Order

表包含与该客户关联的

customer\u id

和

employee\u id

。我知道这涉及到一个子查询，我知道它看起来像这样

SELECT DISTINCT
        Employee.employee_id,
        Orders.customer_id,
        Employee.supervisor_id
FROM    Employee,
        Orders
WHERE   EXISTS ( SELECT customer_id,
                        Employee.employee_id
                 FROM   Orders AS cs2,
                        Employee
                 WHERE  cs2.employee_id = Employee.employee_id
                        AND Employee.supervisor_id = Employee.employee_id
                        AND cs2.customer_id = Orders.customer_id );

---

目前为止，此查询未返回任何结果。

可能是这样的：

SELECT a.employee_id, b.customer_id, a.supervisor_id
FROM   Employee a INNER JOIN Orders b ON a.employee_id = b.employee_id 
       INNER JOIN Orders c ON b.customer_id = c.customer_id
       AND c.employee_id = a.supervisor_id

---

这是MS SQL Server还是MySQL？他们是不同的。