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From: Josh Berkus <josh@agliodbs.com>
Reply-To: josh@agliodbs.com
Organization: Aglio Database Solutions
To: Gregory Brauer <greg@wildbrain.com>, pgsql-sql@postgresql.org
Subject: Re: Trees in SQL
Date: Mon, 27 May 2002 13:06:53 -0700
References: <3CEE818B.9020702@wildbrain.com>
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Message-Id: <200205271306.53646.josh@agliodbs.com>

Greg,

> What sort of strategies are best for storing tree structures in a
> relational database, and how would one structure SQL queries to find,
> say, "all of the children anywhere under this node", or to represent
> the condition "if this node is a child at any depth under this other
> node"?  Are there good strategies for preventing cycles?

Joe Celko covers this extensively in his book "SQL for Smarties."  You shou=
ld=20
definitely buy it and read the two chapters on tree structures before going=
=20
any further.

I will be writing an article for Techdocs within the month on implementing=
=20
Celko's "Linear Nested Sets Model" of trees in PostgreSQL.  If you can't=20
wait, buy the book, e-mail me, and I'll send you my notes.

--=20
-Josh Berkus