Query to get the Line Number for Covered Product in Oracle Service Contracts

SELECT lines.line_number || '.' || prd_lines.line_number line_number,to_char(prd_lines.id)
  FROM okc_k_headers_b hdr
     , okc_k_lines_b lines
     , okc_k_lines_b prd_lines
     , okc_k_items oki
WHERE 1 = 1
   AND lines.dnz_chr_id = hdr.ID
  AND lines.ID = oki.cle_id
   AND hdr.contract_number = :p_contract_number
   AND hdr.contract_number_modifier = :p_modifier
   AND lines.lse_id = 1
   AND prd_lines.dnz_chr_id = hdr.ID
   AND lines.ID = prd_lines.cle_id
   AND prd_lines.lse_id = 9;