How to use join using linq to sql in C#?

Priya Bhatia

i want some sample code on this

Priya Bhatia

oh i found one code example ,
var LeaveTypes = (from l in BlogDbContext.LeaveType
join e in BlogDbContext.User
on new { PID = l.AddedBy } equals new { PID = e.UserId }
select new
{
TypeId = l.TypeId,
LeaveTitle = l.LeaveTitle,
Description = l.Description,
AddedBy = l.AddedBy,
UpdateBy = l.UpdateBy,
CreatedDate = l.CreatedDate,
UpdateDate = l.UpdateDate,
CreatedBy = e.UserName
}

                 ).ToList();

example reference...http://www.codechef4u.com/post/2017/03/05/How-to-use-join-using-linq-to-sql-in-C

website : www.codechef4u.com

Priyasha Sarmah

You could go two ways with this. Using LINQPad (invaluable if you're new to LINQ) and a dummy database, I built the following queries:

Posts.Join(
Post_metas,
post => post.Post_id,
meta => meta.Post_id,
(post, meta) => new { Post = post, Meta = meta }
)

or

from p in Posts
join pm in Post_metas on p.Post_id equals pm.Post_id
select new { Post = p, Meta = pm }

In this particular case, I think the LINQ syntax is clearer.

The thing I'd like to point out though is that if you have appropriate foreign keys in your database, (between post and post_meta) then you probably don't need an explicit join unless you're trying to load a large number of records. Your example seems to indicate that you are trying to load a single post and it's meta data. Assuming that there are many post_meta records for each post, then you could do the following:

var post = Posts.Single(p => p.ID == 1);
var metas = post.Post_metas.ToList();

Priyasha Sarmah

You may go through the following link for help: http://knowledgetpoint.com/csharp/csharp-tutorial/