Question

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

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.

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

Answer 1

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();