[Gvsig_english] Modelling 1:n and m:n relationships in GIS

[Benjamin Ducke]

Dear all,

I keep getting into situations where mapping 1:n and m:n relationships
in relational DBMS to GIS vector models becomes a problem.
The toughest restrictions of course are the 1:1 relation between map
features and attribute table records and the fact that GIS relates
data by spatial overlay, not foreign fields. I realize that some GIS
(like GRASS) are somewhat more flexible in that they can attach more
than one attribute table to a layer, but I am really looking for more
portable ways to deal with this.

- How do you deal with 1:n and m:n relations in GIS?

- What do you do if there are no spatial representations for the
records on the "n" side? Can that be handled at all?

Apparently, it would be possible to model some of this using overlapping
features in Shapefiles, but that would violate topology rules.

Any ideas are very welcome, indeed!

Thanks, everyone, 

Ben

-- 
Benjamin Ducke
Senior Applications Support and Development Officer

Oxford Archaeology
Janus House
Osney Mead
OX2 0ES
Oxford, U.K.

Tel.: ++44 (0)1865 263 800
benjamin.ducke at oxfordarch.co.uk




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