NAME
   GraphViz::DBI - graph database tables and relations

SYNOPSIS
     use GraphViz::DBI;
     print GraphViz::DBI->new($dbh)->graph_tables->as_png;

DESCRIPTION
   This module constructs a graph for a database showing tables and
   connecting them if they are related. While or after constructing the
   object, pass an open database handle, then call `graph_tables' to
   determine database metadata and construct a GraphViz graph from the
   table and field information.

METHODS
   The following methods are defined by this class; all other method calls
   are passed to the underlying GraphViz object:

   new( [$dbh] )
       Constructs the object; also creates a GraphViz object. The
       constructor accepts an optional open database handle.

   set_dbh($dbh)
       Sets the database handle.

   get_dbh()
       Returns the database handle.

   is_table($table)
       Checks the database metadata whether the argument is a valid table
       name.

   is_foreign_key($table, $field)
       Determines whether the field belonging to the table is a foreign key
       into some other table. If so, it is expected to return the name of
       that table. If not, it is expected to return a false value.

       For example, if there is a table called "product" and another table
       contains a field called "product_id", then to indicate that this
       field is a foreign key into the product table, the method returns
       "product". This is the logic implemented in this class. You can
       override this method in a subclass to suit your needs.

   graph_tables()
       This method goes through all tables and fields and calls appropriate
       methods to determine which tables and which dependencies exist, then
       hand the results over to GraphViz. It returns the GraphViz object.

TODO
   *   Test with various database drivers to see whether they support the
       metadata interface.

   *   Make each table a vertical port with dependencies using those ports.

   *   Provide the possibility to name edges to specify the type of
       relationship ('has-a', 'is-a', etc.).

BUGS
   None known so far. If you find any bugs or oddities, please do inform
   the Maintainer. Patches especially welcome.

AUTHOR
   Marcel Gr�nauer <[email protected]>

MAINTAINER
   Aaron Trevena  <[email protected]>

COPYRIGHT
   Copyright 2001 Marcel Gr�nauer. All rights reserved.

   This library is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself.

SEE ALSO
   perl(1), GraphViz(3pm).