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Designing Displays for Interactive Database Access
Event-driven interfaces maximize the user’s choices so that control of an application resides with the user. In the context of database access, you also need to safeguard data from unintended changes. This chapter shows you how to implement an interface, also called a form, that balances user freedom with data protection. Figure 8–3 shows the database access form that this chapter implements.
Figure 8–3: Basic Database Access Form
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A basic database access form has several key features:
- Allows the user to navigate through a set of records
- Displays key data so users know that they are interacting with the correct record
- Separates update mode from display mode and lets users decide whether to save or cancel their changes on a record-by-record basis
- Lets users create new records and lets the user decide whether to keep or discard the new record
- Allows users to delete records, but asks for confirmation before deleting the record
- Handles all foreseeable user errors
In Figure 8–3, the form’s buttons execute triggers that perform these user tasks: navigate and display, update, add, and delete. Figure 8–4 shows how the form and triggers work together.
Figure 8–4: How a Database Access Form Works
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This chapter shows you how to build this fully functional database access form. This simple model is one that you can use in most situations. The form is also flexible enough to accommodate many of the advanced techniques that you can learn about in the Progress Programming Handbook .
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