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C++Builder Database Architecture
and Sybase, the BDE communicates with back-end database servers using SQL Links and/
or ODBC drivers. Often these drivers make calls to native driver libraries supplied by the
DBMS vendor. Figure 12.1 illustrates this relationship.
Figure 12.1.
C++Builder implements
a simple, yet
flexible, databaseaccess
architecture.
Native DBMS driver
Your application
BDE alias
BDE driver
ODBC driver
Within your applications, data-aware controls reference TDatasource components. Usually,
a given form makes use of only a handful of TDatasource controls, although it may include
numerous data-aware components. These components reference one or more TDatasource
controls that, in turn, reference one or more TDatasets. It’s not unusual for a form to include
just one TDataset and one TDatasource. Figure 12.2 illustrates how these elements relate to
one another.
The flexibility inherent in this multilevel architecture makes it quite easy to develop database
applications that are not only robust, but also scalable. Thanks to the separation of the backend
BDE drivers from your front-end application components, it’s at least theoretically
possible to change an application’s database back end without even recompiling the app. The
architecture’s modularity allows individual pieces of it to be replaced without having to
reengineer it or rebuild applications based on it.
Now that I’ve given you a broad overview of the architecture, let me make a few general
statements that may help reinforce the concepts I’ve just discussed. You may be saying, “This
architecture stuff sounds nifty, but how do I use it? How does it apply to me? What does all
this really mean?” If this sounds like you, hopefully the following tips will help crystallize the
discussion thus far.
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