Left join with group by linq lambda expression c#?

Question

I want to write left join using linq lambda expression. I have tried query using join but now I want to create using left join so any one can help me how can do.

Here this is my query:

var UserList = db.UserInfo
                .Join(db.Course, u => u.id, c => c.userid, (u, c) =>
                new { u, c }).GroupBy(r => r.u.id)
                .Select(g => g.OrderByDescending(r => r.c.datetime)
                .FirstOrDefault()).OrderByDescending(a => a.u.datetime).ToList();

Using this query, I don't want user data those who are not in course table, so I want to this data also in course table in userid in or not.

i want to return userinfo data in coruse table user id avaible or not rieght now in course table user id is not then userinfo this user is not getting so i want this user also — coderwill, Mar 31 '17 at 12:57
You can find your solution here http://stackoverflow.com/questions/21537469/how-to-make-left-join-in-lambda-linq-expressions — user2960398, Mar 31 '17 at 12:57
@user2960398 i was looking this link but i don't know how can edit my query can you please edited.. — coderwill, Mar 31 '17 at 12:58
You can find your solution here [http://stackoverflow.com/questions/21537469/how-to-make-left-join-in-lambda-linq-expressions](http://stackoverflow.com/questions/21537469/how-to-make-left-join-in-lambda-linq-expressions) [http://stackoverflow.com/questions/30525830/linq-lambda-left-join-with-an-inner-join](http://stackoverflow.com/questions/30525830/linq-lambda-left-join-with-an-inner-join) [http://stackoverflow.com/questions/12075905/left-outer-join-in-lambda-method-syntax-in-linq](http://stackoverflow.com/questions/12075905/left-outer-join-in-lambda-method-syntax-in-linq) — user2960398, Mar 31 '17 at 12:59

score 0 · Answer 1 · edited May 23 '17 at 12:02

0

you can use

var qry = Foo.GroupJoin(
      Bar, 
      foo => foo.Foo_Id,
      bar => bar.Foo_Id,
      (x,y) => new { Foo = x, Bars = y })
.SelectMany(
      x => x.Bars.DefaultIfEmpty(),
      (x,y) => new { Foo=x.Foo, Bar=y});

ref: How do you perform a left outer join using linq extension methods

edited May 23 '17 at 12:02

Community

1
1

answered Mar 31 '17 at 13:17

Elsunhoty

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i have try this wave but that time i didn't get coruse table any filed in select many. – coderwill Mar 31 '17 at 13:25
hi i am trying this query but getting error not get any records. – coderwill Apr 01 '17 at 06:12

Left join with group by linq lambda expression c#?

1 Answers1