Borland Database Component Types Overview

   

---

This section offers an overview of the component sets offered by Borland for database applications.

Component Sets

Borland provides a variety of component sets for accessing databases.

• BDE ” The Borland Database Engine components are the original component set provided for Borland products. It connects programs with the Borland Database Engine and its database drivers. The BDE provides a common abstraction layer across a variety of database management systems (DBMS) (for more information on these components , see Chapter 8, "The Borland Database Engine.")

• Interbase Express (IBExpress) ” Components very similar to the BDE component set, which are optimized for Borland's Open Source DBMS ”Interbase, and which don't require the BDE to be installed on the client system (for more information on these components, see Chapter 10, "Interbase Express Component Overview.")

• dbExpress ” A lightweight component set with lightweight drivers for widely used client-server databases ”no BDE required. (for more information on these components, see Chapter 12, "Data Access with dbExpress.")

• dbGo ” A component set known as ADO Express prior to C++Builder 6. These components provide an interface to Microsoft's ActiveX Data Objects database drivers (usually referred to as providers). Although dbGo doesn't need the BDE, it also cannot be run under Linux, and, therefore, shouldn't be used in CLX applications. (for more information on these components, see Chapter 11, "ADO Express Components for C++Builder.")

Database components are only as good as their user interface counterparts. Almost every conventional user interface component has a "data aware" counterpart , which can be hooked to a TDataSource . TDataSource components can connect to TDataSet descendants, which, for all of the component sets, are the basic data access components they provide.

Figure 6.1 shows the relationships between these major component subsets in the UML (Unified Modeling Language) notation.

Figure 6.1. The major data components and their relationships.

In this diagram, the arrow with the diamond indicates that components at the diamond end reference an instance of a component from the other end. The arrow indicates a group of components that are derived from the group of components at the arrow end.

Figure 6.2 shows the UML notation for how each component set specializes the TCustomConnection class to provide a connection optimized for the database access model provided by each specific component set.

Figure 6.2. The connection components and their relationships.

In Figure 6.3 you can see the TDataSet descendants for each component class.

Figure 6.3. The TDataSet descendant components and their relationships.

Subsequent chapters will discuss this in some detail, but first, an overview.

---

Top