Creating error message in enter query mode

Question

Thanks u3 and am0x,
Thanks for your answer.Now i want to implement the same thing for another scnerio.
Suppose i have entered a certain date but there is no related data in the database for .I am concedering it as a error and want to show a message.
In the trigger ON-ERROR i have written this code.
DECLARE
err_code NUMBER := ERROR_CODE;
err_type VARCHAR2(3) := ERROR_TYPE;
msg VARCHAR2(2000) := ERROR_TEXT;
BEGIN
IF err_code = 40358 AND err_type = 'FRM' THEN
message('please enter date as 01-jan-2008');
END IF;
IF err_code = 40301 AND err_type = 'FRM' THEN
message('there is no related data in the database ,please enter the value again');
END IF;
RAISE FORM_TRIGGER_FAILURE;
END;
But it is not showing any message if there is no related data in the database can you please help.

Answer 1

That looks like it should work, but you have left out an important line which could tell you why it's not working. If the error code is not one of the two you have specified then there will be no message at all!
Try this and see what error message you get. Perhaps the code is something other than 40301.
DECLARE
  err_code NUMBER := ERROR_CODE;
  err_type VARCHAR2(3) := ERROR_TYPE;
  msg VARCHAR2(2000) := ERROR_TEXT;
BEGIN
  IF err_code = 40358 AND err_type = 'FRM' THEN
    message('please enter date as 01-jan-2008');
  ELSIF err_code = 40301 AND err_type = 'FRM' THEN
    message('there is no related data in the database ,please enter the value again');
  ELSE
    message(err_type||'-'||to_char(err_code)||': '||msg);
  END IF;
  RAISE FORM_TRIGGER_FAILURE;
END;