Database: e_learning
Question: Which course authors teach two or more courses? Give me their addresses and author IDs.
SQL: select t1.address_line_1 ,  t2.author_id from course_authors_and_tutors as t1 join courses as t2 on t1.author_id  =  t2.author_id group by t2.author_id having count(*)  >=  2