For example DbVisualizer can be used to connect to a DB and create nice diagram out of existing tables and their relations. But in this specific case I do not have a live database but I have bunch of create table and alter statements.
Is there any tool to generate similar diagrams out of SQL DDL?
I found the MySQL tool MySQL Workbench to do a great job. There is a Mac OS X version. More information can be found at http://dev.mysql.com/doc/index-gui.html.