PLS-00103, in Trigger - sql

Question

create or replace TRIGGER log_worlds BEFORE UPDATE OR INSERT ON worlds
DECLARE
ac VARCHAR2(50);
tab VARCHAR2(50);
world VARCHAR2(50);
BEGIN
IF UPDATING THEN
ac:='Aktualizacja';
END IF;
IF INSERTING THEN
ac:='Nowe';
END IF;
tab:='WORLDS';
world:='world_';
world:=world||cast(NEW_WORLD.NEXTVAL as VARCHAR2(10));
INSERT INTO log(ACTION_DATE,ACTION,TAB_NAME,ADDED_WORLD) VALUES(SYSDATE,ac,tab,world);
INSERT INTO worlds(WORLD_NAME) VALUES(world);
END;
Can someone help me with this,error information is about line 14? This trigger is supposed to add new values to the log table and to change the primary key value of the worlds table when my APEX application issues DML against the table.

Answer 1

the error you get suggests some syntax error in your code which I can't immediately find. However I would expect another error becuase Oracle won't allow you do execute DML statements (select, insert, update, delete) inside of a trigger on the same table as the trigger is on. Your trigger is on table worlds, so you are not allowed to insert a record into table worlds inside the trigger.

Answer 2

I think it's this line here:
world:=world||cast(NEW_WORLD.NEXTVAL as VARCHAR2(10));
If you replace it with:
world := world||to_char(NEW_WORLD.NEXTVAL);
it should work.
Btw: directly using a nextval call in an assignment does not work on versions prior to 11.x (not sure about the value of x here).
In 10.x you would need to declare a variable and then use:
SELECT to_char(new_world.nextval)
into world_num;
world := world || world_num;

Answer 3

The immediate syntax error is that assuming NEW_WORLD is a sequence you've created, you would need to do something like
SELECT world ||
cast( new_world.nextval as varchar2(10) )
INTO world
FROM dual;
rather than directly referencing the sequence in your CAST.
It's far from clear to me what your trigger is supposed to be doing though. It is, at a minimum, going to generate an infinite loop. Every INSERT on WORLDS is going to cause the trigger to fire which will generate an INSERT on WORLDS which will cause the trigger to fire, etc. Oracle will eventually raise an error when you exceed the maximum recursion depth. Perhaps you intended this to be a row-level trigger rather than a statement-level trigger that changed the value of :new.world_name? If that's the case, you'd probably want something like
create or replace TRIGGER log_worlds
BEFORE UPDATE OR INSERT ON worlds
FOR EACH ROW
DECLARE
ac VARCHAR2(50);
tab VARCHAR2(50);
world VARCHAR2(50);
BEGIN
IF UPDATING THEN
ac:='Aktualizacja';
END IF;
IF INSERTING THEN
ac:='Nowe';
END IF;
tab:='WORLDS';
world:='world_';
select world || cast(new_world.nextval as varchar2(10)
into world
from dual;
INSERT INTO log(ACTION_DATE,ACTION,TAB_NAME,ADDED_WORLD)
VALUES(SYSDATE,ac,tab,world);
:new.world_name := world;
END;
This assumes that world_name is not actually the primary key. If world_name is the primary key then it would make no sense to modify the primary key value when a row is updated-- you would only want to potentially assign the primary key if you are doing an INSERT.