• Try this

    DECLARE @PDFFileName VARCHAR(8000) =

    (

    SELECT STUFF(( SELECT ', ' + PDF_FileName + '.pdf' + char(13) + char(10)

    FROM @PDFResult

    ORDER BY 1 ASC FOR XML PATH(''),type).value('(./text())[1]','Varchar(8000)'),1,1,'')

    )

    Select @PDFFileName