Select *
From
(Select
  Left(ArtistPerson.Name, 1) as Letter,
  Count(ArtistPerson.ArtistPersonID) As Aantal
From
  ArtistPerson,
  (Select Distinct
    ArtistAlbumLink.ArtistPersonID
  From
    ArtistAlbumLink)
Where
  ArtistPerson.ArtistPersonID = ArtistAlbumLink.ArtistPersonID
Group By
  Left(ArtistPerson.Name, 1))
Order By
  Aantal desc
