[postgis-users] Shared geometries?

[Jeff Dege]

Suppose I have a shapefile containing county data, with polygon
geometries representing the county boundaries.  And another shapefile
containing state data, with polygon geometries representing the state
boundaries.

The state boundaries and the county boundaries should coincide, though I
know of no way of enforcing that with shapefiles.

Is there a way, in PostGIS, to create two layers that have different
sets of attributes, but whose gemoetries share the same points?  So that
if I edit the county boundaries, the state boundaries will automatically
reflect those changes?