Can i disable a trigger inside a trigger in oracle? - oracle

Question

I have 2 triggers and two tables.
One(trigger) is to insert inside one column in the other table when a row in first table is inserted, the other one prevent insert and update in that column.
I want to know if there is a way i can disable the second trigger that prevents the insert/update during the execution of first trigger.

Answer 1

This is how I understood the question. See if it helps.
Sample tables:
SQL> create table test (id number);
Table created.
SQL> create table test_2 (id number);
Table created.
A trigger on test_2 which prevents inserts:
SQL> create or replace trigger trg2
2 before insert or update on test_2
3 for each row
4 begin
5 raise_application_error(-20000, 'Not allowed');
6 end;
7 /
Trigger created.
Does it work?
SQL> insert into test_2 (id) values (1);
insert into test_2 (id) values (1)
*
ERROR at line 1:
ORA-20000: Not allowed
ORA-06512: at "SCOTT.TRG2", line 2
ORA-04088: error during execution of trigger 'SCOTT.TRG2'
Yes, it works.
Now, a trigger on test which is supposed to a) disable trg2 trigger and b) insert value into test_2. A straightforward code would then be
SQL> create or replace trigger trg1
2 before insert on test
3 for each row
4 begin
5 execute immediate 'alter trigger trg2 disable';
6 insert into test_2 (id) values (:new.id);
7 end;
8 /
Trigger created.
Let's test it:
SQL> insert into test (id) values (1);
insert into test (id) values (1)
*
ERROR at line 1:
ORA-04092: cannot COMMIT in a trigger
ORA-06512: at "SCOTT.TRG1", line 2
ORA-04088: error during execution of trigger 'SCOTT.TRG1'
Aha. Can't COMMIT in a trigger. Where is it? In dynamic SQL's alter trigger - it is a DDL and it implicitly commits. How to "fix" it? Make it (a trigger) an autonomous transaction:
SQL> create or replace trigger trg1
2 before insert on test
3 for each row
4 declare
5 pragma autonomous_transaction;
6 begin
7 execute immediate 'alter trigger trg2 disable';
8 insert into test_2 (id) values (:new.id);
9 end;
10 /
Trigger created.
SQL> insert into test (id) values (1);
insert into test (id) values (1)
*
ERROR at line 1:
ORA-06519: active autonomous transaction detected and rolled back
ORA-06512: at "SCOTT.TRG1", line 6
ORA-04088: error during execution of trigger 'SCOTT.TRG1'
That's another error; it says that - if we have an autonomous transaction - we have to either commit or roll back. Let's commit (because that's probably what you'd want to do):
SQL> create or replace trigger trg1
2 before insert on test
3 for each row
4 declare
5 pragma autonomous_transaction;
6 begin
7 execute immediate 'alter trigger trg2 disable';
8 insert into test_2 (id) values (:new.id);
9 commit;
10 end;
11 /
Trigger created.
SQL> insert into test (id) values (100);
1 row created.
SQL> select * From test;
ID
----------
100
SQL> select * from test_2;
ID
----------
100
SQL>
Right; now it works.
I suggest you re-read comments posted below your question, see this example and choose what to do.