Borland® Delphi™ 6 Developer's Guide

Using dbExpress

dbExpress is designed to efficiently access data and to carry little overhead. To accomplish this, dbExpress uses unidirectional datasets.

Unidirectional, Read-Only Datasets

The nature of unidirectional datasets means that they don't buffer records for navigation or modification. This is where the efficiency is gained against the bi-directional BDE datasets that do buffer data in memory. Some limitations that result are

• Unidirectional datasets only support the First() and Next() navigational methods. Attempts to call other methods—such as Last() or Prior()—will result in an exception.

• Unidirectional dataset records aren't editable because there is no buffer support for editing. Note, however, that you would use other components ...