LINQ joining two tables

Question

I have two tables say A and B. A cols are GUID, someintVar, someMoreIntvar B col are GUID, someItemNO, SomeItemDesc

Now for one GUID I will have only one row in Table A. But I can have multiple rows for the same GUID. Now I want to query the database based on GUID and select values in a class. This class will have a list that will hold different rows coming from the second table. How can I do it?

Right Now I am getting many items in the result based on how many rows are there in the second table for that GUID.

var itemColl = from p in db.A
               join item in db.B on p.CardID equals item.CardID
               where p.CardID == "some GUID"
               select new 
               {
                   p.CardID,
                   p.secondCol,
                   p.ThirdCol,
                   item.ItemNo // How to add them in a collection or list.
               };

Answer 1

Unested, but how about re-writing it a bit:

var itemColl = from p in db.A
               where p.CardID == "some GUID"
               select new {
                   p.CardID,
                   p.secondCol,
                   p.ThirdCol,
                   Items = db.B.Where(b=>b.CardID==p.CardID)
                      //.Select(b=>b.ItemNo) [see comments]
               }

Alternatively, you could perhaps group...

Answer 2

Assuming this is happening in the NEW or LOAD method of your class...this is how I would do it...

dim myAItem AS A = (from x in db.As WHERE x.CardID == MyGUIDValue).SelectSingleOrDefault

' Assign Variables Here
Me.AValue1 = myAItem.FromDbValue1

dim itemColl = (from b in db.Bs on b == MyGUIDValue).ToList 

me.ItemList = New List(of MySubClass)
For each bItem as B in itemColl
   dim item as New MySubClass
   'Assign Variables Here, ex: item.Value1 = bItem.MyDbValue1
   me.ItemList.Add(item)
Next

Answer 3

Assuming you have a foreign-key relationship set up between A and B on GUID. (And if you don't you db schema is broken and needs to be fixed)

var itemColl = from p in db.A
               where p.CardID == "some GUID"
               select new 
               {
                   p.CardID,
                   p.secondCol,
                   p.ThirdCol,
                   Items = p.Bs
               }