:DONATIONSX.TRANSACTION_NUMBER := :global.shn;
:DONATIONSX.AMOUNT             := :global.amount;

TRANSACTION_NUMBER VARCHAR(10) unique not null

-- WNFI trigger
declare
  l_transaction_number  donationsx.transaction_number%type;
begin
  -- I'm using MAX in order to avoid NO-DATA-FOUND. As this is unique value,
  -- only one value would be returned anyway (if it exists)
  select max(d.transaction_number)
    into l_transaction_number
    from donationsx d
    where d.transaction_number = :global.shn;

  if l_transaction_number is null then
     -- record does NOT exist
     :donationsx.transaction_number := :global.shn;
     :donationsx.amount             := :global.amount;
  else
     -- record already exists - fetch it!
     set_block_property('donationsx', onetime_where, 'where transaction_number = ' || :global.shn);
     go_block('donationsx');
     execute_query;
  end if;
end;

TRANSACTION_NUMBER   VARCHAR (10) UNIQUE NOT NULL

TRANSACTION_NUMBER   VARCHAR (10) PRIMARY KEY

/* Sample When-New-Form-Instance trigger */
/* Code is untested, but should work.    */
DECLARE
   v_def_where   VARCHAR2(250);
BEGIN
   v_def_where := 'transaction_number = '||NAME_IN('GLOBAL.SHN')||' and amount = '||NAME_IN('GLOBAL.AMOUNT');
   Set_Block_Property('DONATIONSX',DEFAULT_WHERE,v_def_where);
   Execute_Query;
END;

...
   CURSOR c1 (p_trans_num VARCHAR2) IS
      SELECT DONATIONS.TRANSACTION_NUMBER, DONATIONS.target, DONATIONS.attending_personnel
            ,DONATIONS.payment_mode, DONATIONS.account_number, DONATIONS.account_name
            ,DONATIONS.branch, DONATIONS.bank_name, DONATIONS.currency_type
            ,DONATIONSx.TRANSACTION_NUMBER,DONATIONSx.amount 
        FROM donations, donationsx
       WHERE donations.transaction_number = donationsx.transaction_number
         AND donations.transaction_number = p_trans_num;
...

...
   OPEN c1(NAME_IN('GLOBAL.SHN'));
   LOOP
      FETCH c1 INTO ...