Use a sequence. Here's an example.

create sequence s ;

Sequence created.


create table t ( c number );

Table created.


insert into t values ( s.nextval );

1 row created.

insert into t values ( s.nextval );

1 row created.

insert into t values ( s.nextval );

1 row created.

insert into t values ( s.nextval );

1 row created.


select * from t;

C
----------
1
2
3
4

4 rows selected.

--
Joe Fuda
SQL Snippets: Tutorials for Oracle Developers