- AppForge Brings Visual Basic to the PalmOS
- Step 1: Create an Access Database
- Step 2: Create a Visual Basic Project
- Step 3: Create Necessary Forms
- Step 4: Add Code
- Conclusion
- Additional Resources
Step 1: Create an Access Database
The PalmOS includes a filesystem that functions as a database, albeit a non-relational one. "Tables" are accessed on an individual basis and any joins that must take place must be "hand-rolled" by the developer. (This is not the case if you're using a commercial database for the PalmOS such as Oracle Lite or IBM's DB/2 Everywhere, but that's a discussion for another article!) AppForge includes a utility that converts Microsoft Access .MDB databases into the .PDB format used by the PalmOS. This process is as simple as creating a database using Microsoft Access and then converting the database using the AppForge Database Converter for Palm (see Figure 1).
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The AppForge Database Converter for Palm.
Our customer database is quite simple, containing fields for a name, company, email address, address, city, state, ZIP, and sales representative. Before converting the file, you'll be prompted for a CreatorID and a Type. These are PalmOS constructs used to uniquely identify a specific database (necessary since all databases are stored in one flat-file system). To reserve a unique ID (important if you're doing commercial PalmOS development), visit http://www.palmos.com/dev/tech/palmos/creatorid/. I completed this process and reserved the CreatorID XZXZ, which you'll see if you analyze the source code included with this example (see Figure 2).
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Setting a database CreatorID and Type.
Once the conversion process has been completed, the converter will ask whether you want to create a Visual Basic code module for working with the database. Choosing OK causes a complete helper module to be created, simplifying routine tasks such as opening the database and getting/retrieving records. This module also contains a new Visual Basic type that represents a single record within this table.