[postgis-users] How to select the highest y-value within all storedobjects

[Norman Vine]

Simon Schneider
> 
> I have a table storing polygon objects and I'm looking for a 
> way to get 
> the highest y-coordinate within all these objects.
> 
> I know which polygon contains this value but I'm wondering 
> whether there 
> is a way to build a query which delivers only coordinates and not the 
> polygon itself.

The envelope of the polygon would sort of give you that

http://postgis.refractions.net/docs/ch06.html#id2912634
ST_Envelope(geometry)

Norman