Data Modeler

Oracle has a free Data Modeler tool. There is a stand alone version of this tool. Another version is bundled with SQL Developer v3 and beyond. Both versions have the same functionality. The stand alone version gives you more screen real estate and easier access to the menus. The tool itself was developed in Java. As such, it requires the JDK.

Data Modeler lets you create, browse, and edit models. Here are some model types it supports:
  • Logical
  • Relational
  • Physcial
  • Multi-dimensional
  • Data Type
You can do forward and reverse engineering with the tool. The targets it supports are Oracle, SQL Server, and DB2. Although I would think you would want to have the tool produce DDL, it cause also spit out other formats like CSV. You can perform collaborative development with this tool.

Why go through the trouble of using a Data Modeler? Some say it is much easier than maintaining scripts manually. It can serve as a documentation tool. Or it can just help you get a handle on an existing database system.