SQL & PL/SQL

Hi there,

I'm posting a message in this forum in order to get some help. I'm working on a database which has been developped by someone and I've some difficulties to insert a new unique barcode in my table ressource.

Actually, I've 2 tables : barcode and ressource. I understand that barcode is there to generate a new barcode which is link to Ressource with the barcode_id. I don't manage to insert new values in my Barcode table. How the barcode is automatically inseted into ressource ?

For example :

Barcode
id
37465
SECTOR
D
YEAR
3
PREFIX
58

Ressource
Barcode | barcode_id
D03000058 37465

I've also a trigger but I don't know how to use it.

create or replace TRIGGER "TBB".TOB_BARCODE
	BEFORE INSERT OR UPDATE ON BARCODE
	FOR EACH ROW
DECLARE 
	integrity_error  exception;
	errno            integer;
	errmsg           char(200);
BEGIN
	-- autoincrement
	IF INSERTING THEN
		BEGIN
			SELECT S_BARCODE.NEXTVAL INTO :NEW.ID FROM dual;
		EXCEPTION
			WHEN integrity_error THEN 
				raise_application_error(errno, errmsg);
		END;
	END IF;
	
  BEGIN
	-- calculated row BARCODE of RESSOURCE table
	UPDATE RESSOURCE SET BARCODE = 	:NEW.SECTOR || TO_CHAR(:NEW.YEAR,'FM00') || TO_CHAR(:NEW.PREFIX,'FM00000') ||
			    					DECODE(:NEW.CATEGORY, 2, 'E', 3, 'D', NULL,'','') || TO_CHAR(:NEW.SUFFIX,'FM00') 
		WHERE BARCODE_ID = :NEW.ID ;
  EXCEPTION
    WHEN OTHERS THEN NULL;
  END;
 
END;