如何使用 SQL 从指定格式的多对多关系中提取数据以用于复选框？

Question

ll The table structure is as shown below.

As an example, I want the enrollment details of a student, let's say the student with ID 3.

I expect the query result to be in the above format.

I intend to use the true / false or 0, 1 column to be linked to a list of check-boxes at the front-end. This way a student can check / uncheck his own enrolled courses easily.

More Info

My project will be created in ASP.Net MVC. So, I am OK with LINQ queries as well. Assume standard model code with no annotations.

EDIT: I didn't write my attempt as I simply didn't get far enough to post it here. But here it is

SELECT COURSE.CNAME, 0
FROM COURSE
union
SELECT COURSE.CNAME, ENROLLMENT.EID
FROM COURSE INNER JOIN ENROLLMENT
ON COURSE.CID = ENROLLMENT.CID
INNER JOIN STUDENTS
ON STUDENTS.SID = ENROLLMENT.SID
WHERE STUDENTS.SID = 3

Answer 1

I think you want a left join . This would give you the result you want for student 3 :

select
    e.eid,
    c.cname,
    c.cid,
    case when e.eid is null then 0 else 1 end as isenrolled
from course c
left join enrollment e on e.cid = c.cid and e.sid = 3
order by is_enrolled desc, e.eid, c.cid