Developing database applications is an ever-evolving process. During the development phase, you can modify the structure and/or datafile. Later on, however, these changes to the structure and/or datafile can become increasingly problematic.
With just a little advance planning, you can make the upgrade process much less burdensome, and even worry-free. This technical note describes a scheme of "building-in" a system that ensures that the data is brought up to par with any structure upgrade. In fact, this scheme is an almost foolproof system that also insures against problems associated with skipping important revision updates if such previous upgrades are missed.
The example database included with this technical note demonstrates the entire process, and the code is generic enough that you should be able to copy it into you own databases with very little effort.