Oracle Database Discussions

hi
i am trying to fetch final PO approver from the database but i am not sure which basic tables to use. i am using following query but it gives me the list of approvers. how do i get the final approver:
SELECT distinct (he.FULL_NAME) "Approver Name",pall.APPROVER_ID
FROM po_requisition_lines_all prla
, po_requisition_headers_all prha
, po_distributions_all pda
, po_headers_all pha
, po_req_distributions_all prda
, po_approval_list_lines pall
, po_approval_list_headers palh
, per_people_f he
WHERE prla.REQUISITION_HEADER_ID =prha.REQUISITION_HEADER_ID
AND prla.REQUISITION_LINE_ID = prda.REQUISITION_LINE_ID
AND prda.distribution_id = pda.req_distribution_id (+)
AND pda.po_header_id = pha.po_header_id (+)
AND prha.REQUISITION_HEADER_ID = palh.document_id
AND pall.approval_list_header_id = palh.approval_list_header_id
AND he.PERSON_ID = pall.APPROVER_ID

can anyone help. thank you.