Question

Dim ds = From a In db.Model
           Join b In db.1 On a.id Equals b.ID
           Join c In db.2 On a.id Equals c.ID
           Join d In db.3 On a.id Equals d.ID
           Join f In db.4 On a.id Equals f.ID
   Select a.id, a.Ref, a.Type, a.etc

Above is my linq query. At the moment I am only getting the first row from the db returned when there are currently 60 rows. Please can you tell me where I am going wrong and how to select all records.

Thanks in advance!

UPDATE:

When I take out all the joins like so:

 Dim ds = From a In db.1, b In db.2, c In db.3, d In db.4, f In db.5
Select a.id, a.Ref, a.type, b.etc, c.etc, d.etc

I get a system.outofmemory exception!

Answer 1

You’re only going to get a row produced when all of the joins match – in other words, when there’s a row from Model with an AP, an Option, a Talk and an Invoice. My guess is that there’s only one of those.

LINQ does an inner join by default. If you’re looking for a left outer join (i.e. where a particular row may not have an Invoice, or a Talk etc) then you need to use a group join, usually in conjunction with DefaultIfEmpty.

I’m not particularly hot on VB syntax, but this article looks like it’s what you’re after.