Identity Columns

Using identity columns you can generate ids. They are similar to default values, but evaluated dynamically.

Example
CREATE TABLE actors (id INTEGER IDENTITY,
              lastname VARCHAR(20),
              surname VARCHAR(20));

INSERT INTO actors (lastname, surname) VALUES
                    ('Pacino', 'Al'),
                    ('Willis', 'Bruce'),
                    ('Pitt', 'Brad');

SELECT * FROM actors;
Results
ID LASTNAME SURNAME
1 Pacino Al
2 Willis Bruce
3 Pitt Brad