Question

我正在使用Mysql。

我有2张桌子：

表销售：

S_Id    DATE       Total_Price    Employee_Id
1       1/02/2014  5636           10
2       1/04/2014  148            999
3       1/05/2014  101            30
4       1/06/2014  959            40
5       1/02/2014  3000           10
6       1/04/2014  4992           13
7       1/05/2014  472            11
8       1/06/2014  8483           40

餐桌员工：

Employee_Id  First_Name    Last_Name    Address     City 
10           brock         li           a1          berlin
20           dan           santiago     a2          london
30           alex          brookmen     a3          rome
40           michael       gold         a4          amsterdam
50           john          bisping      a5          barcelona
999          tony          oneale       a6          munich

雇员表仅包含在职雇员
但仍然保留所有销售额的表Sales，包括未在职员工的销售额

我的问题：

我想让前4名在2015年使每个仅在职员工的总销售额（按Sales.Total_Price总和）最大的员工
Employee_Id = 999将包括他的销售额之和，以及未在职员工的所有销售额之和。
- Employee_Id = 999是在职员工

结果应为：

Employee_Id  First_Name    Last_Name    Address     City    total sales  
10               brock         li          a1       berlin      8636  
20               dan           santiago    a2       london      8483 
999              tony          oneale      a6       munich      5612
40               michael       gold        a4       amsterdam   959

因此，我尝试在Sales表中将左连接到雇员，并在employee.Employee_Id = null时将所有价格相加

我的代码：

SELECT s.employee_id
     , e.first_name
     , e.last_name
     , e.address
     , e.city
     , CASE WHEN ISNULL(e.employee_id) OR e.employee_id = 999 
            THEN SUM(s.total_price) 
            ELSE SUM(s.total_price) END 'total sales'
  FROM sales s
  LEFT 
  JOIN employees e
    ON s.employee_id = e.employee_id
 WHERE YEAR(s.date) = 2015
 GROUP 
    BY s.employee_id
     , e.first_name
     , e.last_name
 ORDER 
    BY SUM(s.total_price) DESC
 LIMIT 4

但没有成功：

它没有将所有空值（非现役员工）的销售额总计到Employee_Id = 999行中
当我只希望活跃员工出现在列表中时，仍然可能没有活跃员工出现在前4名销售额中
此外，如果您知道一种更好的汇总每位员工最多4个销售额的方法，那对我来说很重要

Answer 1

您必须首先对销售表中的所有详细信息求和，然后使用左联接。诸如此类的内容可能会对您有所帮助-

 SELECT E2.*, Total_Sales
 FROM (SELECT emp.employee_id
             ,SUM(total_price) Total_Sales
       FROM (SELECT CASE WHEN e.employee_id IS NULL OR e.employee_id = 999 THEN 999 ELSE s.employee_id END employee_id
                  , e.first_name
                  , e.last_name
                  , e.address
                  , e.city
                  , s.total_price
             FROM Sales s
             LEFT JOIN employees e ON s.employee_id = e.employee_id) emp
             GROUP BY emp.employee_id) s2
 JOIN employees E2 on s2.employee_id = E2.employee_id
 ORDER BY s.total_sales DESC
 LIMIT 4

这是Db小提琴-

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=748fd944384d80e717c08b3a2057f5c6

Answer 2

谢谢你Ankit Bajpai，这是最终答案

select  employees.*, Total_Sales
from    (select emp.Employee_Id,
        sum(Total_Price) as 'Total_Sales'
        from    (select case when employees.employee_id is null or employees.Employee_Id = 999 then 999 else Sales.Employee_Id end Employee_Id,
                Sales.Total_Price
                from      actiview_task.Sales                  
                left join actiview_task.employees
                on        Sales.Employee_Id = employees.Employee_Id
                where year(DATE)= 2015) emp
         group by emp.Employee_Id) empGroupBy
join actiview_task.employees on empGroupBy.Employee_Id = employees.Employee_Id
order by Total_Sales desc
limit 4

SQL：如何将所有空值求和成特定行的另一个值？

2 个答案: