Where are Attachments Stored and how can I get it from database?

Hi,

I use following this script for check my PO Attachment and now I need to clear this attachment but I want to backup those file into another place and then I'll delete by using purge program.

SELECT PH.SEGMENT1 PO_NUMBER,

  --SUM(DBMS_LOB.GETLENGTH(fl.file_data)) SIZE_BYTES,

  ATT.FILE_NAME,

  ATT.CREATION_DATE,

  ATT.entity_name,

  ATT.SEQ_NUM,

  ATT.CATEGORY_DESCRIPTION,

  ATT.DATATYPE_NAME

FROM FND_ATTACHED_DOCS_FORM_VL ATT,

  po_headers_all ph,

  fnd_lobs fl

WHERE function_name           =DECODE(0,1,NULL,'PO_POXPOEPO')

AND to_number(PH.PO_HEADER_ID)= to_number(pk1_value)