To Select Prepayment Invoice Status in Oracle Payables

SELECT   pv.VENDOR_NAME,
           ai.invoice_num,
           NVL (
              DECODE (
                 SIGN (SUM (amount - NVL (prepay_amount_remaining, amount))),
                 1,
                 DECODE (SUM (prepay_amount_remaining), 0, 'Y', NULL),
                 NULL
              ),
              'N'
           )
              AS PP_F     -- Y is Fully Applied, N is Partially or Not Applied
    FROM   ap_invoice_distributions_all aid, ap_invoices_all ai, po_vendors pv
   WHERE       aid.invoice_id = ai.INVOICE_ID
           AND pv.VENDOR_ID = ai.VENDOR_ID
           AND aid.line_type_lookup_code = 'ITEM'
           AND ai.invoice_type_lookup_code = 'PREPAYMENT'
           AND ai.INVOICE_ID = :P_INVOICE_ID
           AND NVL (reversal_flag, 'N') <> 'Y'
GROUP BY   pv.vendor_name, ai.invoice_num
  HAVING   NVL (
              DECODE (
                 SIGN (SUM (amount - NVL (prepay_amount_remaining, amount))),
                 1,
                 DECODE (SUM (prepay_amount_remaining), 0, 'Y', NULL),
                 NULL
              ),
              'N'
           ) <> 'Y';