[mapguide-users] How to use Select Aggregates in MapGuide

[Kenneth Skovhede, GEOGRAF A/S]

I'm having trouble understanding how the "Select Aggregates" system works.
I expect it to be similar to the "GROUP BY" SQL command.

But, on the test page:
http://localhost/mapguide/mapagent/selectfeaturesform.html

I have the fields "Properties" and "Computed Properties".
If I enter nothing in the "Properties" field, or the name of a spatial 
column, I get a "Type error".
If I enter the name of an existing column, I get all the rows containing 
this column.

The "Computed Properties" field seems to accept anything, and has no 
effect on the output.

I would like to calculate the actual extents of the geometry of the 
entire featuresource.
There seems to exist an FDO command called "SpatialExtents", but I don't 
see how I
can use that function from MapGuide.

Any help is appreciated!

-- 
Regards, Kenneth Skovhede, GEOGRAF A/S