Payables invoice prepayment query in Oracle Apps R12

SELECT   pv.vendor_name C_vendor_name,
         pvs.address_line1 C_address_line1,
         pvs.address_line2 C_address_line2,
         pvs.address_line3 C_address_line3,
            DECODE (pvs.city, '', '', pvs.city || ', ')
         || DECODE (pvs.state, '', '', pvs.state || ' ')
         || pvs.zip
            C_city_state_zip,
         pvs.country C_country,
         aipp.last_update_date C_application_date,
         aipp.prepayment_amount_applied C_amount_applied,
         inv.invoice_currency_code C_currency_code,
         pp.invoice_num C_prepay_num,
         inv.invoice_num C_invoice_num,
         NVL (inv.invoice_amount, 0) - NVL (inv.amount_paid, 0)
            C_amt_remaining
  FROM   ap_suppliers pv,
         ap_supplier_sites_all pvs,
         ap_invoices_all inv,
         ap_invoices_all pp,
         ap_invoice_prepays_all aipp
 WHERE       aipp.invoice_id = inv.invoice_id
         AND aipp.prepay_id = pp.invoice_id
         AND inv.vendor_id = pp.vendor_id
         AND inv.vendor_id = pv.vendor_id
         AND pv.vendor_id = pvs.vendor_id
         AND pvs.vendor_site_id = inv.vendor_site_id
         AND NVL (pvs.LANGUAGE, 'AMERICAN') = 'AMERICAN'
         AND aipp.last_update_date >= &InvDate
UNION
SELECT   pv.vendor_name C_vendor_name,
         pvs.address_line1 C_address_line1,
         pvs.address_line2 C_address_line2,
         pvs.address_line3 C_address_line3,
            DECODE (pvs.city, '', '', pvs.city || ', ')
         || DECODE (pvs.state, '', '', pvs.state || ' ')
         || pvs.zip
            C_city_state_zip,
         pvs.country C_country,
         aid2.last_update_date C_application_date,
         NVL (
            ap_invoices_utility_pkg.get_pp_amt_applied_on_date (
               inv.invoice_id,
               pp.invoice_id,
               aid2.last_update_date
            ),
            0
         )
            C_amount_applied,
         inv.invoice_currency_code C_currency_code,
         pp.invoice_num C_prepay_num,
         inv.invoice_num C_invoice_num,
         NVL (inv.invoice_amount, 0)
         - (ap_invoices_pkg.get_prepaid_amount (inv.invoice_id))
            C_amt_remaining
  FROM   ap_suppliers pv,
         ap_supplier_sites_all pvs,
         ap_invoices_all inv,
         ap_invoices_all pp,
         ap_invoice_distributions_all aid1,
         ap_invoice_distributions_all aid2
 WHERE       aid1.invoice_id = inv.invoice_id
         AND aid2.invoice_id = pp.invoice_id
         AND aid2.invoice_distribution_id = aid1.prepay_distribution_id
         AND aid1.line_type_lookup_code = 'PREPAY'
         AND inv.vendor_id = pp.vendor_id
         AND inv.vendor_id = pv.vendor_id
         AND pv.vendor_id = pvs.vendor_id
         AND pvs.vendor_site_id = inv.vendor_site_id
         AND NVL (aid1.reversal_flag, 'N') != 'Y'
         AND NVL (pvs.LANGUAGE, 'AMERICAN') = 'AMERICAN'
         AND inv.invoice_date >= &InvDat