[postgis-users] Extents

[Sean M. Montague]

I need to return the extent or multiple geometries, I tried the below
statement, but it returned nothing.  Is there a way to return the extent
of the combined extents?  Thanks

Sean

SELECT EXTENT(the_geom)
>From trails_02a
WHERE objectid = 1 AND objectid = 2 AND objectid = 3;