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