Question

我有一个包含分配表和员工表的数据库。每个表都包含员工ID。多个员工在同一个项目上工作，我需要能够获得每个项目ID和工作小时数的员工姓名列表。我尝试了以下但是它无法正常工作。

Select FirstName, LastName, ProjectID, HoursWorked
From employee e, assignment a
Where e.EmployeeNumber = a.EmployeeNumber
Group by projectID;

编辑：在第一个回答后，我将查询更改为：

SELECT  FirstName, LastName, ProjectID, HoursWorked
FROM    employee e, assignment a
Where e.EmployeeNumber = a.EmployeeNumber
GROUP   BY ProjectID, FirstName, LastName;

结果很好，我不完全理解我想的那个小组。

Answer 1

您需要使用聚合函数 SUM()才能获得列的总值，

SELECT  FirstName, 
        LastName, 
        ProjectID, 
        SUM(HoursWorked) totalHoursWorked
FROM    employee e
        INNER JOIN assignment a
            ON e.EmployeeNumber = a.EmployeeNumber
GROUP   BY FirstName, LastName, ProjectID

查找所有员工的姓名以及每个项目ID的工时

1 个答案: