Query to Join OM and Purchase Order tables for Back 2 Back Order

select ph.segment1,a. supply_source_line_id, a.supply_source_header_id
from
mtl_reservations a,
oe_order_lines_all l,
po_headers_all ph
where demand_source_line_id = &Enter_Order_lineID
and l.line_id = a.demand_source_line_id
and a.supply_source_header_id = ph.po_header_id