GraphViz::DBI - graph database tables and relations


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


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.


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.


Sets the database handle.


Returns the database handle.


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.


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.


  • 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.).


None known so far. If you find any bugs or oddities, please do inform the author.


Marcel Grünauer <>


Copyright 2001 Marcel Grünauer. All rights reserved.

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


perl(1), GraphViz(3pm).