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C++Builder Database Architecture
■ You do not need the TQuery or TStoredProc components unless you’re writing your
own SQL or accessing server-based stored procedures. You can open database tables
in any of the local or remote formats supported by C++Builder using just the
TTable component.
■ You’ll normally use the TTable component to send/receive data from databases. As
mentioned, TTable is the centerpiece of C++Builder’s database access. You use it to
reference database tables and to exchange data with data-aware controls.
■ The components on the Data Controls page are visual, data-aware controls—they
allow data to be displayed and allow users to change the data visually. They’re “data
smart” versions of the controls you often see in Windows applications. You’ll use
these components to build the user interface of database applications. They interact
with data access controls such as TTable to provide users with database access.
■ TDataset descendants (for example, TTable, TQuery, and TStoredProc) retrieve data
from databases, but they cannot supply this data directly to data-aware components
(such as TDBEdit); they need TDatasource to function as the conduit between them
and your application’s data-aware controls. This means that data-aware components
such as TDBEdit do not refer directly to the TDataset that provides their data
access. Instead, they reference a TDatasource that, in turn, references a TDataset.
■ So, to build a simple data-aware form you need three things: a TTable, a
TDatasource, and whatever data-aware controls the form requires (TDBEdit,
TDBMemo, and so on).
A Tour of the C++Builder Database
Components
Now that you’ve received a basic overview of the C++Builder database architecture, let’s cover
the components individually. I’ll go through C++Builder’s database components one by one
and discuss the key elements of each. I’ll build on the general discussion of the database
architecture by giving you a thorough tour of the C++Builder database components that
encompass it.
I’ve intentionally omitted components that act only as support classes. If a class is not actually
a component—that is, if it’s merely an ancestor of a component—I don’t include it. This
includes the TDataset and TDBDataSet classes, for example. They’re class ancestors of the
TTable, TQuery, and TStoredProc components. My emphasis here is on components that you
can manipulate using C++Builder’s visual tools. Although the ancestor class hierarchy is
important, most of the properties, events, and methods you’ll need to be aware of are
provided in C++Builder’s components by design.
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