Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

1. rm-hull/sql_graphviz is a small Pyton script that generates a Graphviz visualization of a SQL schema dump.

2. sqldep - queryScope is a great online tool for visualizing logic of SQL code. You need to sign up in order to use this tool.

3. queryViz is another online tool for visualizing logic of SQL code but with very limited functionalities.

4. eralchemy is a a tool for visualizing entity relationship in a SQL database.