mysql - 计算每个销售代表的佣金

Question

有点卡在这个上了..

问题:计算每位销售代表的佣金，假设佣金为订单成本的 5%。按员工姓氏和名字排序。

对于这个数据库.. http://richardtwatson.com/dm6e/images/general/ClassicModels.png

这是我所拥有的..

SELECT salesRepEmployeeNumber, amount * orderNumber AS commission, 
 CONCAT(firstName, ' ', lastName) AS sales_rep
  FROM Customers, Payments, Employees, Orders
    WHERE Payments.customerNumber= Customers.customerNumber
      AND (amount * orderNumber) * .05`

`

但显然这个查询没有任何结果!

TIA

Answer 1

好吧，我想我可能已经弄清楚了..如果有更简单的方法，请告诉我!

SELECT Customers.salesRepEmployeeNumber, CONCAT(firstName, ' ', lastName) AS Employee, (amount*5)/100 AS commission
FROM Customers, Payments, Employees
WHERE Payments.customerNumber= Customers.customerNumber
ORDER BY lastName, firstName;