Representing pedigree tree in SQL

In article <91615c$j8$1_at_nnrp1.deja.com>,   Joe Celko <71062.1056_at_compuserve.com> wrote: >
> Another way of representing trees is to show
 them as nested sets.
> Since SQL is a set oriented language, this is a
 better model than the
> usual adjacency list approach you see in most
text books. Let us

I working on a general solution to representing pedigree trees, which don't seem to fit very well into the nested set model, even after repeated readings of 'SQL for Smarties'!

In a pedigree any given individual can participate in the tree at several levels.
For example in a pedigree of cats, the same tom can potentially be great-grandfather, grandfather, and father to a litter of kittens.

The situation is even more complex for plant pedigrees, where an individual may be both mother and father, at the same level and at different levels in the pedigree.

I'm looking at duplicating the hierarchy for each place the individual node appears in the tree, but can't help feeling that there's a far better solution somewhere.

Any suggestions, or pointers to books/articles, both on and offline, received with
thanks.

• Chris Hutchinson

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http://www.deja.com/ Received on Wed Dec 20 2000 - 05:33:29 CET