plpgsql_func_get_actor_by_id

-- Definição da Function
CREATE OR REPLACE FUNCTION get_actor_fullname(in_actor_id INT)
RETURNS VARCHAR AS $$
DECLARE
    full_name VARCHAR DEFAULT '';
BEGIN
    full_name := (
        SELECT first_name || ' ' || last_name
        FROM actor
        WHERE actor_id = in_actor_id
    );
    RETURN full_name;
END
$$ LANGUAGE plpgsql;

-- PARA TESTAR, chame a Function!
SELECT get_actor_fullname(15);