Re: support virtual generated column not null constraint

This scenario fails

1. CREATE TABLE person (
    id INT GENERATED BY DEFAULT AS IDENTITY,
    first_name VARCHAR(50) NOT NULL,
    last_name VARCHAR(50) NOT NULL
);

2. INSERT INTO person (first_name, last_name)
VALUES ('first', 'last');

3. ALTER TABLE person
ADD COLUMN full_name VARCHAR(100) GENERATED ALWAYS AS (first_name || ' ' || last_name) VIRTUAL;