Query to get PO details by passing Requisition number

SELECT pha. po_header_id,
               pha. segment1 "po number",
               prha .segment1 "req number"
FROM 

               po_headers_all pha,
               po_distributions_all pda ,
               po_req_distributions_all prda ,
               po_requisition_lines_all prla ,
               po_requisition_headers_all prha
WHERE 1=1
AND      pha. po_header_id = pda. po_header_id
AND      pda. req_distribution_id = prda.distribution_id
AND      prda. requisition_line_id = prla. requisition_line_id
AND      prla. requisition_header_id = prha. requisition_header_id
AND      prha. segment1 = '19';