LINQ to SQL Left Outer Join

Hi,

Is this query equivalent to a LEFT OUTER join?

//assuming that I have a parameter named 'invoiceId' of type int
from c in SupportCases
let invoice = c.Invoices.FirstOrDefault(i=> i.Id == invoiceId)
where (invoiceId == 0 || invoice != null)    
select new 
{
      Id = c.Id
      , InvoiceId = invoice == null ? 0 : invoice.Id
}

From stackoverflow

• Not quite - since each "left" row in a left-outer-join will match 0-n "right" rows (in the second table), where-as yours matches only 0-1. To do a left outer join, you need SelectMany and DefaultIfEmpty, for example:

      var query=  from c in db.Customers
                  join o in db.Orders
                     on c.CustomerID equals o.CustomerID into sr
                  from x in sr.DefaultIfEmpty()
                  select new {
                     CustomerID= c.CustomerID, ContactName=c.ContactName,
                     OrderID = x.OrderID == null ? -1 : x.OrderID};
  

  (or via the extension methods)

• Public Sub LinqToSqlJoin07()
  Dim q = From e In db.Employees _
          Group Join o In db.Orders On e Equals o.Employee Into ords = Group _
          From o In ords.DefaultIfEmpty _
          Select New With {e.FirstName, e.LastName, .Order = o}
  
  ObjectDumper.Write(q) End Sub
  

  Check http://msdn.microsoft.com/en-us/vbasic/bb737929.aspx