How to query multiple tables in linq

[nanak]

i all.

i have three tables named forum , topics & posts  i want some columns from forum table and according to the forumid i want total topics available & post available

here is the query i am using but don't know exactly how it will work.

    you may have seen on many forum websites they show forum name total topics in it and total posts in it. i want the exact same.

    public IQueryable GetAllForums_TopicsCount_PostCount()
        {
            eld = new ELearnDataContext();
            var query = from n in eld.Forums
                        join m in eld.ForumTopics
                        on n.ForumID equals m.ForumID
                        select new { n.IconFile, n.Title, n.Description, n.DateCreated
                       
                     
                       
                        };
            return query;
        }

[Serge]

Hello Nanak,

It seems that you have taken the wrong approach here. I will assume that you have collection members on each class, by that I mean the forum class has a collection property of type topics and the topic class has a collection property of type post. If you do not have such properties in your model I suggest reading "Defining a Domain Model" section of the OpenAccess help installed on your machine as well as having a look at the LINQ 101 Samples that are also installed on your machine (you can also find them online here).

However if you do have such a model your code for accessing this should look a little like this : 

using (ElearnDataContext context = new ElearnDataContext())
{
    foreach (Forum forum in context.Forums)
    {
        Console.WriteLine(forum.Topics.Count);
        Console.WriteLine(forum.Topics.Sum(x => x.Posts.Count));
    }
}

I hope this helps. If  you need further information please do not hesitate to contact us back.

Best wishes,
Serge
the Telerik team