I have two tables - forum_topics and topics_posts. I want to select rows from forum_topics which have no posts in the topics_posts table, but cannot figure out how to. Does an SQL statement like this exist:
select from * `forum_topics` where have no rows in `topics_posts` I think you want something like that:
select * from forum_topics t where not exists ( select * from topics_posts p where p.topic_id = t.id ); Although using an outer join, might be a bit faster than the subquery:
select * from forum_topics t left outer join forum_posts p on t.id = p.topic_id where p.id is null; 