Database Modeling and Design

9.1 Introduction to the CASE Tools 189
Figure 9.2
Database design process
broadest set of technology partners, and third-party training. What it
does it does well, but in recent years it has lagged in some advanced features.
Sybase’s PowerDesigner has come on strong in the past few years,
challenging AllFusion ERwin. It has some advantages in reporting and
some advanced features that will be described later in this chapter. IBM’s
Rational Data Architect is a new product that supplants IBM’s previous
product, Rational Rose Data Modeler. Its strength lies in strong design
checking; rich integration with IBM’s broad software development platform,
including products from their Rational, Information Management,
and Tivoli divisions; and advanced features that will be described below.
In previous chapters, we discussed the aspects of logical database
design that CASE tools help design, annotate, apply, and modify. These
include, for example, ER, and UML modeling, and how this modeling
can be used to develop a logical database design. Within the ER relationship
design, there are several types of entity definitions and relationship
modeling (unrelated, one-to-many, and many-to-many). These relationships
are combined and denormalized into schema patterns known as
normal forms (e.g., 3NF, star schema, snowflake schema). An effective
design requires the clear definition of keys, such as the primary key, the
foreign key, and unique keys within relationships. The addition of constraints
to limit the usage (and abuses) of the system within reasonable
bounds or business rules is also critical. The effective logical design of