Mysql 显示员工的销售计数

我有三张桌子。个人详细信息、员工和订单。“个人详细信息”包含有关姓名和内容的数据。Employee表包含专业数据。订单有销售历史记录

表格个人详细信息

personalID    FirstName    LastName
 1              test         test
 2              test         test
 3              test         test
 4              test         test
 5              test         test

表1员工：

EmployeeID    personalID     hireDate     Status
001              1            test         test
002              2            test         test
003              3            test         test
004              4            test         test
005              5            test         test
and more data

表顺序：

 OrderID   customerID   EmployeeID    ShipmentStatus 
  1            10           002            P             
  2            182          001            P
  3            22           005            P
  4            10           002            P
  5            89           003            P
  6            76           004            P
  7            99           001            P
  8            111          001            P
  9            123          002            P
 10            647          001            P              

我希望得到的最终结果如下：

employeeID     FirstName,LastName   Count(sales to customers)
   001           test test                  4
   002           test test                  3
   003           test test                  1
   004           test test                  1
   005           test test                  1

到目前为止，我有：

SELECT e.employeeID, Concat (p.firstName,' ', p.lastName) AS Name, o.customerID
FROM Employee ((
INNER JOIN PersonalDetail ON e.personalID = p.personalID)
INNER JOIN Orders ON e.employeeID = o.employeeID)
ORDER BY employeeID;

这给了我以下结果：

employeeID    Name            CustomerID
001           test test          182
001           test test          99
001           test test          111
001           test test          647
002           test test          10
002           test test          10
002           test test          123
003           test test          89
004           test test          76
005           test test          22

---

我知道如何根据每个客户订单显示员工姓名，但却难以显示特定员工的订单数量。

您可以加入并聚合：

select
    e.EmployeeID,
    concat(e.FirstName, ',', e.LastName) employeeName,
    count(*) no_sales
from employees e
inner join sales s on s.EmployeeID = e.EmployeeID
group by e.EmployeeID, e.FirstName, e.LastName
order by no_sales desc

---

要避免“订单依据”错误，请使用计数本身：

select
        E.EmployeeID,
        concat(E.FirstName, ',', E.LastName) employeeName,
        count(S.*) no_sales
    from employees E
    inner join sales S  on S.EmployeeID = E.EmployeeID
    group by E.EmployeeID, E.FirstName, E.LastName
    order by count(S.*) desc

---

提示：加入。分组依据。请仅选择一个RDM