LINQ table join with entity Framework

Question

Hi there,

In my datbase I have TableA, TableB and TableC

TableB has just 2 columns, the primary key of TableA and TableC, so it really defines a one to many relationship between the two tables

What i want to do using SQL is:

SELECT * 
FROM TablesA a
JOIN TablesB b ON a.AID = b.AID
WHERE b.BID = 1

In the Entity Framwork is doesn't create a TablesB for me to do the join, i think because TableB only has foreign keys!

So how can i do it?

Answer 1

Doing a join with LINQ is fairly straightforward

from a in TablesA
join b in TablesB
on a.AID equals b.AID
into joined
where b.BID == 1
select joined

I think the real question may be - why don't you have an entity class for TablesB? We may need more information to answer that.

Answer 2

When you import the tables from database, entity framework gets rid of the TableB table and shows TableA and TableC to have many to many relationships. TableA has a navigation property TableCs and vice versa. So all you need to use these navigation properties, for sample:

var tableARow= db.TableA.First(s => s.Id == 1); 
if (!tableARow.TableCs.IsLoaded) { tableARow.TableCs.Load(); }

or

var tableARow= db.TableA.Include("TableCs").First(s => s.Id == 1);