CREATE TABLE student_tests_taken (registration_id NUMBER, date_test_taken TIME, test_result CLOB)
CREATE TABLE course_authors_and_tutors (author_id NUMBER, author_tutor_atb CLOB, login_name CLOB, password CLOB, personal_name CLOB, middle_name CLOB, family_name CLOB, gender_mf CLOB, address_line_1 CLOB)
CREATE TABLE students (student_id NUMBER, date_of_registration TIME, date_of_latest_logon TIME, login_name CLOB, password CLOB, personal_name CLOB, middle_name CLOB, family_name CLOB)
CREATE TABLE student_course_enrolment (registration_id NUMBER, student_id NUMBER, course_id NUMBER, date_of_enrolment TIME, date_of_completion TIME)
CREATE TABLE subjects (subject_id NUMBER, subject_name CLOB)
CREATE TABLE courses (course_id NUMBER, author_id NUMBER, subject_id NUMBER, course_name CLOB, course_description CLOB)

What are the addresses of the course authors who teach either 'operating system' or 'data structure' course.
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"
SELECT "T1"."address_line_1" FROM "course_authors_and_tutors" "T1" JOIN "courses" "T2" ON "T1"."author_id" = "T2"."author_id" AND ("T2"."course_name" = "data structure" OR "T2"."course_name" = "operating system")