How to decoded the attachment file which is sender through the mail from the backend ?

1.How to decoded the attachment file which sender through the mail from the backend ?

I am sending the mail from backend with attached PO. Mail was send but not able to open the file. How to decoded the file which send from the backend.

SELECT FILE_NAME

       FROM fnd_lobs

       WHERE FILE_ID =

          (SELECT MEDIA_ID

           FROM FND_DOCUMENTS

           WHERE DOCUMENT_ID IN

                (SELECT DOCUMENT_ID

                 FROM FND_ATTACHED_DOCUMENTS

                 WHERE   PK1_VALUE =  (SELECT TO_CHAR (PO_HEADER_ID)

                       FROM PO_HEADERS_ALL

                       WHERE SEGMENT1 = :PO_NUMBER) ))) ;

How to decoded the file in SQL query.