Android ContentResolver query DISTINCT

SDカード内のaudioファイルを検索する場合

String[] projection = {"DISTINCT " + MediaStore.Audio.Media.ARTIST};
String selection = null;
String[] selectionArgs = null;
String sortOrder = null;

ContentResolver contentResolver = getContentResolver();
Cursor cursor = contentResolver.query(
                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                projection,
                selection,
                selectionArgs,
                sortOrder);