Thanks for your help, Would you have an example of the type of aggregate function to use. Afraid we're relative novices with postgres
Cheers strk-2 wrote: > > On Tue, Oct 12, 2010 at 02:14:55AM -0700, dicky1980 wrote: > >> For eaxmple we have >> >> EVENT_ID Time >> 1 12.00 >> 1 12:01 >> 1 12:02 etc >> 1 >> 1 >> 2 >> 2 >> 2 >> 2 >> 1 >> 1 >> >> What we'd like to be able to do is have it draw one line for the first >> event >> id group of 1s, then stop, draw a line for 2's, stop that line then start >> a >> new line for the next group of ones. What > > You'll need to roll your own aggregate function to do that. > Aggregates maintain a state and visit each row in turn. > By feeding the aggregate with your table ordered on Time > you can have a state function checking for EVENT_ID changes > and closing the line there (or at end of input). > > Interesting use case indeed. > > --strk; > > () Free GIS & Flash consultant/developer > /\ http://strk.keybit.net/services.html > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > > -- View this message in context: http://old.nabble.com/Makeline-help-tp29941457p29942017.html Sent from the PostGIS - User mailing list archive at Nabble.com. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
