EF中的多对多关系linq查询 [英] Many to many relation linq query in EF

问题描述

我有3个表Student，Course和链接表StudentCourse，在给定学生ID = 1的情况下，如何返回所有课程，还包括其中学生ID可能不为1并且与该学生的课程相同的行ID 1?结构是这样的:

I have 3 tables Student, Course, and the linking table StudentCourse, how do i return all the courses given a student Id = 1 but also include row where the student id might not be 1 and is taking same course as student of id 1? The stucture is like this:

    student        courses     studentcourse
         1           8            1 -  8
         2           9            2 -  8
         3           10           3 -  9

所以棘手的部分是我还想包括课程8或ID为1的学生修读的任何其他课程的其他行.

so the tricky part is that i also want to include the other rows for course 8 or any other course taken by Student of id 1.

最终结果应该是2行:where子句将指定我对学生id = 1(这是id 8的课程)的课程感兴趣，但是我也想包括该课程的其他行.结果是:

the final result should be 2 rows: the where clause will specify that I am interested in the course where student id = 1 (which is course of id 8) but i also want to include the other rows from that course. So the result is :

1 -  8
2 -  8

推荐答案

鉴于这是EF，您的最新说明是，您在Student实体上应具有Courses导航属性，而在Course实体，您可以执行以下操作:

Given that this is EF and your latest clarification you should have a Courses navigation property on your Student entity and a Students navigation on your Course entity that would allow you to do the following:

var students =  db.Students
                  .Single(x=> x.Id == 1)
                  .Courses.SelectMany(c=> c.Students)
                  .Distinct();

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