Look for all questions where two users have contributed with any of question, answer or comment
Q&A about the site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language
-- Look for all questions where two users have both contributed -- in the form of question, answer or comment select coalesce(parentid,id) from posts where owneruserid=##UserA## --1396 or exists(select * from comments where postid=posts.id and userid=##UserA##) intersect select coalesce(parentid,id) from posts where owneruserid=##UserB## --807 or exists(select * from comments where postid=posts.id and userid=##UserB##) order by coalesce(parentid,id) desc