Mike Nicewarner

Many modelers are confused by overlaps in the data modeling terminology from the various vendors, and are not sure how to compare modeling tools when trying to buy one. This article will attempt to shed some light on this topic, and hopefully answer some of the more frustrating questions. With data modeling, there are three models to deal with. First is the conceptual model, geared toward the business as a way to describe data requirements at a high level. Next is the physical model used to describe the precise schema used by the database platform. Finally, there is the logical model, used to tie the conceptual and physical models together and communicate with other IT groups. Some experts call for subdividing the conceptual into subject area, high-level, and fully attributed to communicate with the various business areas. Most modeling vendors support logical and p... (more)

PowerDesigner 7.5 Beta Review by Sybase

Although still in beta, version 7.5 of the PowerDesigner Suite (PD7.5) from Sybase is a stable product. As the fifth iteration of the Dolphin code rewrite, it's mature and highly functional. To examine what PD7.5 looks like, let's walk through it. I like conceptual modeling, so this is where I usually begin. I'm using PowerDesigner version 7.5.0 build 715, the second beta release of the product. Getting Started What you'll find in PD7.5 that's not in the 7.0 release: Test data generation: Complete and very functional Database size estimation: Also complete and accurate More DBMS... (more)

PowerDesigner 8.0 Beta

PowerDesigner is a very good data modeling tool, but with UML gaining acceptance in many IT shops, Sybase has gradually added object modeling features. In November, they started another beta program named Beluga primarily to add Use Case and Sequence diagrams, but also to fix some problems with packages and enhance the overall user interface. As with previous PowerDesigner betas, Beluga is stable and closer to a shipping product than any other beta I've seen. It should be generally available by the end of February 2001. I'm using PowerDesigner version 8.0.0 build 132, the first ... (more)

Sybase PowerDesigner: Impact Analysis

Sybase has recently included impact analysis features into the PowerDesigner (PD) modeling tool. If you aren't familiar with PD, it's a powerful tool for modeling business processes, data designs, XML messages, and application logic (ala UML). Within each model, you can view the dependent objects (basically, what would be affected if you deleted something). By using the repository, you get generational dependencies added to the mix, giving you a very powerful impact analysis. But that isn't all. PD has introduced a new type of model that links other models to each other. This is ... (more)

Rules of Data Normalization

In this article, I discuss and provide examples of the many rules of data normalization. Currently I count at least seven, which are: Eliminate repeating groups: Make a separate table for each set of related attributes and give each table a primary key. Eliminate redundant data: If an attribute depends on only part of a multivalued key, remove it to a separate table. Eliminate columns not dependent on the key: If attributes do not contribute to a description of the key, remove them to a separate table. Isolate independent multiple relationships: No table may contain two or more ... (more)