Question

为写得不好的标题道歉。

我有两张桌子。表a包含学生ID和姓名，表b包含学生ID，课程和课程费用

我希望能够查询数据库，以便显示学生姓名和课程花费的总金额

到目前为止，我有这个：

SELECT Student.fname, Student.lname, SUM(m.CourseCost) FROM 
  (SELECT DISTINCT StuID, CourseCost FROM Courses) AS m 
     INNER JOIN Student ON m.StuID = Student.ID;

当我尝试运行查询时，Visual Studio会引发错误。我使用MS Access作为数据库。我认为我的内心存在问题

Answer 1

您的查询应该是

SELECT Student.fname, Student.lname, SUM(m.CourseCost) FROM 
  (SELECT DISTINCT StuID, CourseCost FROM Course) AS m 
     INNER JOIN Student ON m.StuID = Student.ID
     group by Student.fname, Student.lname

或者你可以通过其他方式做到

select Student.fname, Student.lname, SUM(m.CourseCost) as  CourseCost
from Student
inner join Course m on Student.ID = m.StuID
group by Student.fname, Student.lname, m.StuID

Answer 2

select students.name , (select sum(cost) from course_details where student_id = students.id) as cost from students;

请注意，这是一个postgresql查询。我相信子查询的概念是一样的。

Answer 3

尝试此查询

 SELECT fname+' '+lname Name,courseName , SUM(CourseCost) CourseCost
    FROM Student 
    INNER JOIN Courses ON Courses.StuID = Student.ID
    GROUP BY fname, lname ,courseName ;

SQL查询在一个表上求和值并从另一个表中选择名称

3 个答案: