How to clear DBMS_ERROR_CODE in 6i ?

Question

I have a problem when I customize a message handling function. This function is on the ON-ERROR trigger of all forms.
The function look like this
DECLARE
     dbenum NUMBER := DBMS_ERROR_CODE;
     dbetxt VARCHAR2(80) := DBMS_ERROR_TEXT;
BEGIN
     message(dbetxt);
END;
On the first form, I insert a record that violate a PK constraint.
I exit the first form, enter a second form. Do a query entering a invalid date and get the 'ORA-00001 index violation on TABLE1.PK_1' message even if the query have nothing to do with the first form.
It look like DBMS_ERROR_CODE is not cleared when I exit one form and enter another. How can I clear it ?
Is this a bug for form6i or this behavior is normal?

Answer 1

DBMS_ERROR_CODE holds the last error returned by the server, no matter what error your form encountered. Instead, you should be displaying this sort of message in your on-error trigger:
DECLARE
  Err_Code NUMBER(5)     := ERROR_CODE;
  MSG     VARCHAR2(150)
          := SUBSTR('   '||ERROR_TYPE||'-'||TO_CHAR(Err_Code)||': '
                                     ||ERROR_TEXT,1,150);
BEGIN
  IF Err_Code=40735
  Or Err_code between 40501 and 40599 THEN
     -- displays error from server --
    Message(MSG);
    Message(DBMS_ERROR_TEXT');
  ELSE
    -- Displays the FRM- error message --
    Message(MSG);
  END IF;
  Raise Form_Trigger_Failure;
END;