drop sequence myseq;
drop table test;
drop table audit_test;

create table test ( a number primary key, b number);
create sequence myseq;
create table audit_test (  myseq number,
                        a number, 
                        program varchar2(128), 
                        machine varchar2(128)
);

create or replace trigger insert_test
     before   insert   on test
     for each row

DECLARE
BEGIN
  insert into audit_test values (mySeq.nextval,:new.a,null,sys_context('USERENV', 'HOST')  );
END;
/