On Fri, Apr 29, 2005 at 12:51:46PM -0500, Dave Rolsky wrote: > On Fri, 29 Apr 2005, kellan wrote: > > >Actually recurrence exceptions are one really good reason why its hard > >to ever come up with an elegant, purely rule based recurrence > >representation. For events involving humans its inevitable that > >sometimes this month's occurrence will get cancelled or re-scheduled. > > Well, the trick is to make complex recurrences like this an actual data > type in the DBMS. > > SELECT ... > FROM RecurringEvent > WHERE OVERLAPS(recurrence, $start_date, $end_date) > UNION > SELECT ... > FROM Event > WHERE start_date >= $start_date > AND end_date <= $end_date > > See how nice and simple that is ;) > > Surely implementation of that data type is just a SMOP! > > Hehe. Actually, if there were a DBMS that supported writing custom data > types in Perl we'd be a long way towards that goal.
[Idle comment from the peanut gallery] I wonder if recurrences could be mapped to OpenGIS Geometry Model using some arbitrary mapping. Then to check for OVERLAPS(...) you'd use INTERSECTION(...) Just a thought... Tim. p.s. Since Postgres has been mentioned already I'll mention MySQL :) http://dev.mysql.com/doc/mysql/en/spatial-extensions-in-mysql.html
