Query on AME Approval for Purchase requisition

We are in 12.1.3. Planning to build a rule  in AME for Purchase Requisition approval - Pickup the  requester's Supervisor  and  send the  Approval to Requester's Supervisor. We are using the below dynamic SQL for creating the approval Group.

select 'PER:'|| paf.supervisor_id

   from po_requisition_headers_all poh,

     po_requisition_lines_all pol,

     per_all_people_f ppf,

     per_all_assignments_f paf

where pol.requisition_header_id = poh.requisition_header_id

and poh.requisition_header_id = :transactionId

and pol.line_num = (select min(line_num)

                              FROM po_requisition_lines_all

                              where requisition_header_id = :transactionId)

and ppf.person_id = pol.to_person_id