Tell me the personal name of the course author that teaches the course with name "operating system".
select t1.personal_name from course_authors_and_tutors as t1 join courses as t2 on t1.author_id = t2.author_id where t2.course_name = "operating system"
How about his address?
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"
Tel me the addresses of the course authors who teach the course with name "operating system" or "data structure"
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"