SQL 查询转换为 Django ORM

Question

select
    l.student_id,
    SUM(l.sum_result)
FROM
    (
        SELECT
            w.student_id,
            w.subject_id,
            r.total as sum_result
        from
            Student w
            INNER JOIN (
                SELECT
                    COUNT(r.id) as total,
                    r.subject_fk_id
                from
                    Result r
                GROUP BY
                    r.subject_fk_id
            ) r ON w.subject_id = r.subject_fk_id
    ) l
GROUP BY
    student_id

The tables are:

Student
-------------
-> id(PK)
->student_name
->student_email


Subject
--------------
-> id(PK)
-> subject_name


Results
---------------
->id (PK)
->subject_fk(FK to subject table)
->date

学生和学科有一个多对多表

Student_Subject
->id(PK)
->Student_id(FK)
->Subject_id(FK)

我想将此 SQL 查询转换为 Django ORM 我需要检索学生的结果总数。我需要在 Django 中编写这个查询 没有 for 循环的 ORM。提前谢谢你

Answer 1

您的查询缺少关系部分，您也可以将查询简化为：

select s.student_id,count(r.id)
from students s 
Join student_subject ss 
 on ss.studentid = s.studentid
join subject sb
 on sb.subject_id = ss.subject_id
join result r
 on r.ssid = ss.id 
group by s.student_id

所以现在我认为您可以轻松地自己编写等效的 ORM，对吗？ ;)