Find the addresses of the course authors who teach the course with name "operating system" or "data structure".
create table courses (author_id varchar, course_name varchar, PRIMARY KEY (author_id)); create table course_authors_and_tutors (address_line_1 varchar, author_id varchar, PRIMARY KEY (address_line_1))
select t1.address_line_1 from course_authors_and_tutors as t1 join courses as t2 on t1.author_id = t2.author_id where t2.course_name = "operating system" or t2.course_name = "data structure"