full jion
http://stackoverflow.com/questions/7978663/mysql-full-join
https://dev.mysql.com/worklog/task/?id=1604
self join
http://databases.about.com/od/sql/a/selfjoin.htm
full jion
http://stackoverflow.com/questions/7978663/mysql-full-join
https://dev.mysql.com/worklog/task/?id=1604
self join
http://databases.about.com/od/sql/a/selfjoin.htm