Database Modeling and Design

190 CHAPTER 9 CASE Tools for Logical Database Design
the database will have a profound impact on the performance of the system,
as well as the ease with which the database system can be maintained
and extended.
There are several other CASE products that we will not discuss in this
book. A few additional products worth investigating include Datanamic’s
DeZign for Databases, QDesigner by Quest Software, Visible
Analyst by Standard, and Embarcadero ER/Studio. The Visual Studio
.NET Enterprise Architect edition includes a version of Visio with some
database design stencils that can be used to create ER models. The cost
and function of these tools vary wildly, from open source products up
through enterprise software that costs thousands of dollars per license.
The full development cycle includes an iterative cycle of understanding
business requirements; defining product requirements; analysis and
design; implementation; testing (component, integration, and system);
deployment; administration and optimization; and change management.
No single product currently covers that entire scope. Instead,
product vendors provide, to varying degrees, suites of products that
focus on portions of that cycle. CASE tools for database design largely
focus on the analysis and design, and to a lesser degree testing, of the
database model and creation as illustrated in Figure 9.2.
CASE tools provide software that simplifies or automates some of the
steps described in Figure 9.2. Conceptual design includes steps such as
describing the business entities and functional requirements of the database;
logical design includes definition of entity relationships and normal
forms; physical database design helps transform the logical design
into actual database objects, such as tables, indexes, and constraints. The
software tools provide significant value to database designers by:
1. Dramatically reducing the complexity of conceptual and logical
design, both of which can be rather difficult to do well. This
reduced complexity results in better database design in less time
and with less skill requirements for the user.
2. Automating transformation of the logical design to the physical
design (at least the basic physical design). This not only reduces
time and skill requirements for the designer, but significantly
removes chances of manual error in performing the conversion
from the logical model to the physical data definition language
(DDL), which the database server will “consume” (i.e., as input)
to create the physical database.
3. Providing the reporting, round trip engineering, and reverse engineering
that make such tools invaluable in maintaining systems