I'm expanding our user/group system to allow for dynamic groups which are made up of other groups members. I have three tables users, groups, and relationships. For simplicity sake, lets say users ...
I know this question has been asked probably a million times, so please forgive me asking it again. I am not a DBA and have very little knowledge of SQL and Derby, but need some kind of a solution as ...
I have to plan a plan tree based on relational algebra.My question is that at some point I have a SORT ORDER BY the output of a join, so how do you represent group by in relational algebra.