Linq union for extra row not from table - sql

Question

VB examples please
I need to return the same results from linq as I get using SQL
SELECT DISTINCT Area, Region
FROM dbo.Regions
Union
SELECT null,'All'
Order by 1,2
I use this for showing an "All" selecting in a combo box
My current linq points to a view that does the union for me but I want to know how to do it right in linq. I can't figure out how to union a row for the null,'All' values.
Public Shared Function GetRegions(ByVal Area As String) As IEnumerable
Dim DB As New SiteDBDataContext
Return From values In DB.uv_Areas _
Where values.Area = Area Or Area = "" Or values.Area Is Nothing _
Order By values.Region _
Select values.Area, values,Region
End Function
Thanks

Answer 1

You can't do it in the DB with Linq to SQL or Entity Framework, but you can do it in memory with Linq to Objects:
Public Shared Function GetRegions(ByVal Area As String) As IEnumerable
Dim DB As New SiteDBDataContext
Dim query = _
From values In DB.uv_Areas _
Where values.Area = Area Or Area = "" Or values.Area Is Nothing _
Order By values.Region _
Select New With { values.Area, values.Region }
Dim all = { New With { .Area = DirectCast(Nothing, String), .Region = "All } }
Return all.Concat(query)
End Function