Trigger won' t work when logged with another user sqldeveloper - oracle

Question

First of all I am a newbie to ORACLE and I am just working for a school project.
I want to create a trigger that triggers every time someone else than the user named 'ion' performs a DDL command.
When logged on other user, to have access to Ion's tables I used this command:
alter session set current_schema = ion;
Here is the code:
set serveroutput on;
CREATE OR REPLACE TRIGGER t12
BEFORE CREATE OR DROP OR ALTER ON SCHEMA
BEGIN
dbms_output.put_line('LALA');
IF UPPER(USER) != 'ION' THEN
RAISE_APPLICATION_ERROR(-20022, 'Only Ion can do this');
ELSE
INSERT INTO audit_ion VALUES(SYS.LOGIN_USER, SYS.DATABASE_NAME, SYS.SYSEVENT, SYS.DICTIONARY_OBJ_NAME, SYSDATE);
END IF;
END;
/
alter session set current_schema = ion;
create table dummy(d integer);
And it creates the table, and not even LALA is printed, so it means it doesn't even enter the trigger. How can I do this ?

Answer 1

From my point of view, you should actually REVOKE all privileges you want to prevent by that trigger.
Meanwhile, as of a trigger, you should have probably checked dictionary_obj_owner instead of user.
I don't have your users (and don't feel like creating that ion) so I'm using my own scott and mike.
SQL> show user
USER is "SCOTT"
SQL> CREATE TABLE audit_ion (
2 login_user VARCHAR2(10),
3 database_name VARCHAR2(10),
4 sysevent VARCHAR2(15),
5 dictionary_obj_name VARCHAR2(20),
6 datum DATE
7 );
Table created.
SQL>
SQL> CREATE OR REPLACE TRIGGER t12 BEFORE CREATE OR DROP OR ALTER ON scott.SCHEMA BEGIN
2 dbms_output.put_line('lala');
3 --IF upper(user) != 'SCOTT' THEN
4 IF upper(dictionary_obj_owner) != 'SCOTT' then
5 raise_application_error(-20022, 'Only Scott can do this');
6 ELSE
7 INSERT INTO audit_ion VALUES (
8 sys.login_user,
9 sys.database_name,
10 sys.sysevent,
11 sys.dictionary_obj_name,
12 sysdate
13 );
14
15 END IF;
16 END;
17 /
Trigger created.
SQL>
Testing (still connected as scott):
SQL> create table trg_test (a number);
Table created.
Altering the session:
SQL> alter session set current_schema = mike;
Session altered.
SQL> create table trg_test (a number);
create table trg_test (a number)
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-20022: Only Scott can do this
ORA-06512: at line 5
SQL> alter session set current_schema = scott;
Session altered.
SQL> select * from audit_ion;
LOGIN_USER DATABASE_N SYSEVENT DICTIONARY_OBJ_NAME DATUM
---------- ---------- --------------- -------------------- --------
SCOTT XE CREATE TRG_TEST 05.01.22
SQL>
Kind of works.