Programming Visual Basic for the Palm OS

Chapter 3. Palm Database Programming

Palm programs, like other programs, typically use some form of persistent data storage. In Chapter 2, we examined how to access the application preferences database to store and retrieve state information, but this form of storage is best suited for small amounts of data. The Palm database manager is the tool of choice for an application’s working data.

In this chapter, we first explain what the Palm OS database manager is and how it works. We’ll look at the different types of databases the Palm supports, and explain the physical layout and characteristics of the most common database—the Palm data file (PDB).

Then we show you how to access the Palm database features via the AppForge PDB library, which provides all the functionality needed to create and manipulate databases and records. We introduce many of the database features with snippets of code showing how the library is used. We also explain the AppForge database schema extensions, which free you from many bookkeeping chores normally associated with Palm database programming.

Next, we cover a very useful AppForge database tool: the Database Converter. This Windows program converts Microsoft Access databases into Palm PDB files for use in your applications.

Finally, we provide an example application that reinforces the material introduced both in Chapter 2 and in this chapter. We have migrated parts of the North Wind Traders Inventory application—a standard example program distributed by ...