SELECT * FROM pre_forum_thread WHERE dateline NOT IN (SELECT dateline FROM pre_forum_post) AND tid >338318;
SELECT * FROM pre_forum_post WHERE tid NOT IN (SELECT tid FROM pre_forum_thread);
delete FROM `pre_forum_thread`和`pre_forum_posts` WHERE authorid NOT IN (SELECT uid FROM pre_ucenter_members);
delete FROM `pre_forum_post` WHERE tid NOT IN (SELECT tid FROM pre_forum_thread);
DELETE FROM pre_home_friend WHERE (uid NOT IN (SELECT uid FROM pre_common_member) OR fuid NOT IN (SELECT uid FROM pre_common_member));
DELETE FROM pre_ucenter_friends WHERE (uid NOT IN (SELECT uid FR ...