Besides generating scripts that create the database, many tools generate scripts for other purposes, such as loading the database with data and updating databases. Some tools let you generate database objects, stored-procedure code, and trigger code.
Another must-have feature for most designers is the ability to update a database by making design changes to its data models. Changing a database's design through its data models provides an easy way to accommodate a company's evolving data needs. More important, it helps preserve the integrity of the database because you're not patching it - instead, you're updating it using the same methodologies and instruments you used to design it. You can also make sure the changes don't negatively affect performance.
Nice Features to Have
As I've said, DFDs and data structure diagrams are nice but not essential features to have in a database design tool. A few other features also fall into the nice-to-have category, such as the ability to undo and redo changes when building the model, and version control, which lets you save different versions of a model for archiving, comparison, and modification purposes.
Advanced reporting capabilities are also nice-to-haves. Most database design tools let you produce reports in several formats (e.g., .html, .rtf) and export diagrams as image files. But some tools also offer capabilities such as customizable report templates and an add-on for creating Web sites that display data models.
The Bottom Line
Database design tools can include numerous features and capabilities - too many to discuss all the possibilities here. If you're in the market for a database design tool, it's worthwhile to identify particular special features you might want. For example, if you're a member of a database design team, you'll probably want a tool that has a central repository for storing designs.
All these tools provide more capabilities than SQL Diagrammer does and go a long way toward making you more productive and helping you build the fast, flexible databases you need. Generally speaking, the more features and capabilities a tool has, the more it costs. If your budget allows you only one bell or whistle, opt for automation. Nine times out of 10, other features and capabilities will be included as part of the automation package.