> Can anyone advice about a tool to visualize a database schema?
SQLalchemy, a Python module, can produce dot (Graphviz) output which you
can load into your favourite diagramming application such as e.g.
Omnigraffle, yEd or Dia:
http://www.sqlalchemy.org/trac/wiki/UsageRecipes/SchemaDisplay
Since this can be automated, it's nice for documentation work.
For inclusion in LaTeX documents, the dot output can then be converted
to TikZ with dot2tex, which is also implemented in Python:
http://www.fauskes.net/code/dot2tex/documentation/
If you're looking for DB modeling tools, here's a pretty comprehensive
list:
http://www.databaseanswers.org/modelling_tools.htm
Sincerely,
Wolfgang Keller