Unions in PostgreSQL

Create the Database with this script: https://github.com/AlexTheAnalyst/PostgresqlYouTubeSeries

Practice Postgresql here: https://www.analystbuilder.com/questions

In this series I want to teach you Postgresql! It's one of the most popular types of SQL right now and is becoming even more popular with the rise of AI. I'll teach you all the syntax and how to use it as well as go beyond just querying!

Code:
CREATE TABLE character_info_extra (
character_id SERIAL PRIMARY KEY,
character_name TEXT NOT NULL,
species TEXT,
planet_id INT,
ship_id INT,
estimated_net_worth NUMERIC(12,2),
has_both_arms CHAR(1),
birth_date DATE
);

INSERT INTO character_info_extra
(character_name, species, planet_id, ship_id, estimated_net_worth, has_both_arms, birth_date)
VALUES
('Ahsoka Tano', 'Togruta', 3, NULL, 220000.00, 'Y', '1985-10-14'),
('Mace Windu', 'Human', 4, 5, 950000.00, 'Y', '1950-02-03'),
('Rey', 'Human', 1, 2, 120000.00, 'Y', '1999-04-10'),
('Finn', 'Human', 1, NULL, 45000.00, 'Y', '1992-07-21'),
('Poe Dameron', 'Human', 2, 1, 310000.00, 'Y', '1982-03-09'),
('General Hux', 'Human', 7, NULL, 80000.00, 'Y', '1984-11-18'),
('BB-8', 'Droid', 2, 6, 5000.00, 'Y', '2014-01-01'),
('Kylo...