create generator g1;
create table t1(
pk smallint primary key,
f1 smallint not null,
f2 smallint not null);
commit;
set term ^;
create trigger tr1 for t1
active before insert as
begin
 new.pk=gen_id(g1,1);
end^
set term ;^
commit;
insert into t1(f1, f2) values (1, -1);
insert into t1(f1, f2) values (2, -2);
insert into t1(f1, f2) values (3, -3);
insert into t1(f1, f2) values (4, -4);
insert into t1(f1, f2) values (5, -5);
insert into t1(f1, f2) values (6, -6);
insert into t1(f1, f2) values (7, -7);
insert into t1(f1, f2) values (8, -8);
insert into t1(f1, f2) values (9, -9);
insert into t1(f1, f2) values (10, -10);
commit;
select max(f1), max(f2) from t1;
MAX   MAX
10   -1