Atualize a base de linha em uma consulta de caminho distinta, material

UPDATE t
SET accno = p.accno 
FROM [table 1] t
INNER JOIN (
SELECT
    DISTINCT fileref, stuff(
        (
        Select char(13)+char(10) + IsNull( D2.viaccno, '' )
        From vi_accno As D2
        Where D2.vifileref = A.FileRef
        For Xml Path(''), type
        ).value('.', 'nvarchar(max)')
        , 1, 2, '') As accno
FROM
   vtindex a
) as p
ON p.fileref= t.fileref