Using QDesigner

Everybody should be doing data modeling. Entity relationship diagrams (ERD) serve as the blueprints for your logical and physical database designs. Can you really imagine a contractor building your house without blueprints? How would you feel if the contractors just started nailing things together based upon their experience and intuition? Well, that's how many databases are put together. It's no wonder that their performance and ability to meet business requirements often fall far short of the desired goal.

QDesigner provides world-class ERD-based, physical data modeling. QDesigner can completely forward- and reverse-engineer database designs, with support for over 30 popular database platforms. QDesigner offers far more features and advanced capabilities than can be described in a few short paragraphs. But for TOAD users, a brief intro on how to reverse-engineer a database into a data model and then forward-engineer that model to generate DDL scripts should suffice to demonstrate QDesigner's usefulness .

To reverse-engineer an existing Oracle database into a QDesigner data model, you perform the following steps:

1. Initiate QDesigner's Reverse Engineering Wizard and specify the source database platform as shown in Figure 10.20. Remember, QDesigner supports over 30 different databases and their numerous versions.

   Figure 10.20. QDesignerReverse Engineering Wizard.

   

2. Identify the desired database connection information and reverse-engineering options as shown in Figure 10.21. QDesigner can generally infer foreign key relationships in the data model even for databases where referential integrity is not being utilized. Plus QDesigner can also infer primary key constraints for databases just using indexes. This is useful when working with databases built for older versions of Oracle.

   Figure 10.21. QDesignerReverse Engineering Options.

   

3. Select the schema, object types, specific objects, and other options to reverse-engineer as shown in Figure 10.22. Note the total objects selected counter in the bottom right-hand corner of this screen. The more items you pick, the longer it will take to reverse-engineer and more complicated your data model will be.

   Figure 10.22. QDesignerReverse Engineering selection.

   

4. You now can work with the data model of your database as shown in Figure 10.23. QDesigner offers far too many features to elaborate any further.

   Figure 10.23. QDesignerphysical data model.

   

To forward-engineer a QDesigner model into a DDL script for the modeled objects, you perform the following steps.

1. Initiate QDesigner's Forward Engineering Wizard (that is, Generate Database) and specify the target database generation options as shown in Figure 10.24.

   Figure 10.24. QDesignerForward Engineering Wizard.

   

2. Review, modify (if needed) and then execute the generated DDL script as shown in Figure 10.25. Of course, that script can be loaded into TOAD's SQL Editor for review and execution.

   Figure 10.25. QDesignergenerated DDL script.