Přepište pomocí MAX(CASE...) a GROUP BY:
select
field1
, [1] = max(case when RowID = 1 then field2 end)
, [2] = max(case when RowID = 2 then field2 end)
, [3] = max(case when RowID = 3 then field2 end)
, [4] = max(case when RowID = 4 then field2 end)
from (
select
field1
, field2
, RowID = row_number() over (partition by field1 order by field2)
from tblname
) SourceTable
group by
field1
Odtud můžete přidat pole3, pole4 atd.