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From: mikharakiri_nospaum@yahoo.com (Mikito Harakiri)
Newsgroups: comp.databases,comp.databases.theory
Subject: Re: Support of SQL recursive queries (over cyclic graphs)
Date: 27 Oct 2004 14:53:23 -0700
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giorgio.terracina@tiscalinet.it (Giorgio) wrote in message news:<38b58a78.0410270341.2b7182c1@posting.google.com>...
> Hi, 
> 
> Anyone knows if some DBMS supports SQL recursive queries over cyclic
> graphs?

DB2, Oracle already support them. SQLServer is adding recursive "with"
implementation next year.
 
> I mean, I know that some DBMS supports recursive queries (SQL3) but
> only on Tree-like data structures (e.g. finding an anchestor, etc.)

There is no such limitation. 
 
> I need to perform queries like "find all pairs of nodes connected by a
> path in a (possibly cyclic) graph", where the graph is represented by
> a relation Arc(x,y) stating all the pairs of nodes x and y directly
> linked by an arc in the graph.
> 
> I tried with Oracle and DB2, but they not seem to  support cyclic
> graphs, only trees.

You need to try harder. A chapter on Recursive Queries in DB2 cookbook
is a good start.