Namespace Samples
    Class Program
        Shared Sub Main()
        Dim dbPath As String = System.IO.Path.GetFullPath(System.IO.Path.Combine(Application.StartupPath, "..\..\Data\NORTHWIND.MDF"))
            Dim sqlServerInstance As String = ".\SQLEXPRESS"
            Dim connString As String = "AttachDBFileName='" + dbPath + "';Server='" + sqlServerInstance + "';user instance=true;Integrated Security=SSPI;"

            Dim path As String = System.IO.Path.GetFullPath(System.IO.Path.Combine(Application.StartupPath, "..\..\Northwind.xml"))
            Dim mappingSource As XmlMappingSource = XmlMappingSource.FromXml(File.ReadAllText(path))
            Dim db As Northwind = New Northwind(connString, mappingSource)
            db.Log = Console.Out
            Samples.Sample10(db) ' как выводить, допустим в TextBox
        End Sub
    End Class
End Namespace 

Public Class Samples
Public Shared Sub Sample10(ByVal db As Northwind)
            ' Используйте оператор группировки (Group By) и статистические функции, такие как Min() и Max(), для вычисления значений по разделам групп
            Dim q = From p In db.Products _
                    Group p By p.CategoryID Into Group _
                    Select New With { _
                        .Category = CategoryID, _
                        .MinPrice = Group.Min(Function(p) p.UnitPrice), _
                        .MaxPrice = Group.Max(Function(p) p.UnitPrice) _
                        }
            ObjectDumper.Write(q, 1)
        End Sub
End Class

Public Class ObjectDumper
    Public Shared Sub Write(ByVal o As Object)
        Write(o, 0)
    End Sub

Public Shared Sub Write(ByVal o As Object, ByVal depth As Integer)
        Write(o, depth, Console.Out) 
    End Sub

Public Shared Sub Write(ByVal o As Object, ByVal depth As Integer, ByVal log As TextWriter)
        Dim dumper As New ObjectDumper(depth)
        dumper.writer = log 
        dumper.WriteObject(Nothing, o)
End Sub 

Private Sub WriteObject(ByVal prefix As String, ByVal o As Object)
        If (o Is Nothing OrElse TypeOf o Is ValueType OrElse TypeOf o Is String) Then
            WriteIndent()
            Write(prefix)
            MsgBox("prefix = " + prefix)

            WriteValue(o)
            WriteLine()
        ElseIf TypeOf o Is IEnumerable Then
            For Each element As Object In CType(o, IEnumerable)
                 If (TypeOf element Is IEnumerable AndAlso Not TypeOf element Is String) Then
                    WriteIndent()
                    Write(prefix)
                    Write("...")
                    WriteLine()
                    If (level < depth) Then
                        level += 1
                        WriteObject(prefix, element)
                        level -= 1
                    End If
                Else
                    WriteObject(prefix, element)
                End If
            Next
        Else
            Dim t As Type
            Dim members As MemberInfo() = o.GetType.GetMembers((BindingFlags.Public Or BindingFlags.Instance))
            WriteIndent()
            Write(prefix)
            Dim propWritten As Boolean = False

            For Each m As MemberInfo In members
                Dim f As FieldInfo = TryCast(m, FieldInfo)
                Dim p As PropertyInfo = TryCast(m, PropertyInfo)
                If (f IsNot Nothing OrElse p IsNot Nothing) Then
                    If propWritten Then
                        WriteTab()
                    Else
                        propWritten = True
                    End If
                    Write(m.Name)
                    Write("=")
                    If (f IsNot Nothing) Then
                        t = f.FieldType
                    Else
                        t = p.PropertyType
                    End If

                    If (t.IsValueType OrElse t Is GetType(String)) Then
                        If (f IsNot Nothing) Then
                            WriteValue(f.GetValue(o))
                        Else
                            WriteValue(p.GetValue(o, Nothing))
                        End If
                    ElseIf GetType(IEnumerable).IsAssignableFrom(t) Then
                        Write("...")
                    Else
                        Write("{ }")
                    End If
                    End If
            Next
            If propWritten Then WriteLine()

            If (level < depth) Then
                For Each m As MemberInfo In members
                    Dim f As FieldInfo = TryCast(m, FieldInfo)
                    Dim p As PropertyInfo = TryCast(m, PropertyInfo)
                    If (f IsNot Nothing OrElse p IsNot Nothing) Then
                        If (f IsNot Nothing) Then
                            t = f.FieldType
                        Else
                            t = p.PropertyType
                        End If

                        If (Not (t.IsValueType OrElse t Is GetType(String))) Then
                            Dim value As Object
                            If (f IsNot Nothing) Then
                                value = f.GetValue(o)
                            Else
                                value = p.GetValue(o, Nothing)
                            End If
                            If (value IsNot Nothing) Then
                                level += 1
                                WriteObject((m.Name & ": "), value)
                                level -= 1
                            End If
                        End If
                    End If
                Next
            End If
        End If
    End Sub