Making an exception abort the insert it triggered

Question

I have a trigger that runs off of an insert statement. The trigger checks the fields inserted and, if necessary, throw a user-defined exception.
The exception is thrown correctly, but the insert statement is still added to the database. How can I prevent this particular statement from being inserted?

Answer 1

Here's an example of raising a user-defined exception in the trigger and then handling that exception in the calling program and continuing:
sql>create table t (c integer);
Table created.
sql>create or replace trigger t_trg
  2    before insert on t
  3    for each row
  4  declare
  5    e_myexception  exception;
  6    pragma exception_init(e_myexception, -20000);
  7  begin
  8    if :new.c = 2 then
  9      raise e_myexception;
10    end if;
11  end;
12  /
Trigger created.
sql>declare
  2    e_trigger_not_happy  exception;
  3    pragma exception_init(e_trigger_not_happy, -20000);
  4  begin
  5    for i in 1..3 loop
  6      begin
  7        insert into t values (i);
  8      exception
  9        when e_trigger_not_happy then
10          null;  -- continue with the loop
11      end; 
12    end loop;
13  end;
14  /
PL/SQL procedure successfully completed.
sql>select * from t;
        C
        1
        3