On Wed, 27 Sep 2006, Dan Libby wrote: > Background: > > I have a hierarchical table where I have coordinate data for only the leaf > nodes. I therefore want to find the center of all the leaf nodes under a > given parent node, and set the parent node coordinate to that center point. > > I can calcululate that center point using aggregate functions (min, max) to > find the necessary x,y values. So my query would look something like this: > > update parent_table set col = > (select (max(pnt[0])-min(pnt[0]))/2+min(pnt[0]) || ',' || > max(pnt[1])-max(pnt[1])/2+min(pnt[1]) from point_tmp where condition) > where condition2 ; > > Where point_tmp.tmp is defined as a point column. > > However, when I try to do it, I get a similar error: > > column "col" is of type point but expression is of type text > > If the above task can be performed some other way, perhaps I don't require > string concatenation.... I don't have 8.0.x to check, but there's likely a point(double precision, double precision) function you can use.
