Using Databases

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Delphi includes many components for accessing databases and representing the information they contain. They are grouped according to the data access mechanism:

• dbExpress
• ADO Components
• The InterBase page of the Component palette contains components that access InterBase databases directly, without going through a separate engine layer.
• The Data Access page of the Component palette contains components that can be used with any data access mechanism. This page includes TClientDataset, which can work with data stored on disk or, using the TDataSetProvider component also on this page, with components from one of the other groups. For more information about using client datasets, see Using provider components
• The BDE page of the Component palette contains components that use the Borland Database Engine (BDE). The BDE defines a large API for interacting with databases. Of all the data access mechanisms, the BDE supports the broadest range of functions and comes with the most supporting utilities. It is the best way to work with data in Paradox or dBASE tables. However, it is also the most complicated mechanism to deploy. For more information about using the BDE components, see Using the Borland Database Engine.

Warning: The Borland Database Engine (BDE) has been deprecated, so BDE will not be enhanced. For instance, BDE will never have Unicode support. You should not undertake new development with BDE. Consider migrating your existing database applications from BDE to dbExpress.

Note: Different versions of Delphi include different drivers for accessing database servers using the BDE, ADO, or dbExpress.

When designing a database application, you must decide which set of components to use. Each data access mechanism differs in its range of functional support, the ease of deployment, and the availability of drivers to support different database servers.

In addition to choosing a data access mechanism, you must choose a database server. There are different types of databases and you will want to consider the advantages and disadvantages of each type before settling on a particular database server.

All types of databases contain tables which store information. In addition, most (but not all) servers support additional features such as

• Database security
• Transactions
• Referential integrity, stored procedures, and triggers

See Also

• Designing the User Interface
• Using the Borland Database Engine
• Understanding Datasets
• Database Architecture
• Connecting to Databases