Reputation: 375
I'm new to LINQ and Lambda. I want to make query that will get me for every studyYear (1,2,3) students who are studying that year. I've done it without Lambda but I really want to know how to do it with lambda.
var res = from s in db.student
join u in db.EnrolledYear
on s.ID equals u.studentID
join g in db.studyYear
on u.studyYearID equals g.ID
select new
{
Year = g.year,
StudentFName = s.FirstName
StudentLName = s.LastName
};
I checked out other examples with lambda but I didn't really understand . What I managed is to make inner join between student and enrolled year. Now I don't understand how to finish inner join between enrolled year and study year. I'm stuck here, I need to make one more join:
var res = db.EnrolledYear.Join(db.student,
u => u.studentID, s => s.ID,
(enroll, student) => new
{
Godina = enroll.year,
FName = student.FirstName
LName = student.LastName
})
.Join(.....?)
Upvotes: 0
Views: 914
Reputation: 584
Use Include
.
Something like:
db.students.Include(x => x.EnrolledYears).ThenInclude(x=>x.StudyYear).Select(new ...)
Upvotes: 3
Reputation: 134621
Every clause in a query will correspond to a lambda call. Just go down to every clause and convert to an appropriate call.
This particular query could be written like so:
db.student
.Join(db.EnrolledYear, s => s.ID, u => u.studentID, (s, u) => new { s, u })
.Join(db.studyYear, x => x.u.studyYearID, g => g.ID, (x, g) => new { x.s, x.u, g })
.Select(x => new
{
Year = x.g.year,
StudentFName = x.s.FirstName,
StudentLName = x.s.LastName,
});
Upvotes: 0